TCP/IP for CICS Systems Programmers

Alfred B Christensen alfredch@us.ibm.com

IBM Raleigh, NC, USA
Session: 8281
Friday, March 4, 2011: 8:00 AM-9:00 AM

TCP/IP for CICS Systems Programmers

Session number:

8281

Date and time:

Friday, March 4, 2011: 8:00 AM-9:00 AM

Location:

Room 205B (Anaheim Convention Center)

Program:

Application Architecture Development

Project:

CICS

Track:

Application Technologies and Architectures and CICS Systems Programming

Classification:

Technical

Speaker:

Alfred B Christensen, IBM

Abstract:

In the past, the CICS systems programmer had to consider and understand how SNA and
VTAM can impact CICS end-user response time and availability. Similar issues now must be
addressed in regards to TCP/IP. In this session the speaker will discuss TCP/IP as it relates to
the CICS systems programmer. The speaker will review CICS and TCP/IP parameters and
highlight areas that might require customization depending on your site's TCP/IP network
configuration. If your installation has, or is about to implement TCP/IP in CICS, come to this
session and learn that there is much more to enabling TCP/IP in CICS than simply specifying
TCP=YES in the SIT.

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2011 SHARE and IBM Corporation

Trademarks, notices, and disclaimers

The following terms are trademarks or registered trademarks of International Business Machines Corporation in the United States or other countries or both:
Advanced Peer-to-Peer
Networking
AIX
alphaWorks
AnyNet
AS/400
BladeCenter
Candle
CICS
DataPower
DB2 Connect
DB2
DRDA
e-business on demand
e-business (logo)
e business(logo)
ESCON
FICON

GDDM
GDPS
Geographically Dispersed
Parallel Sysplex
HiperSockets
HPR Channel Connectivity
HyperSwap
i5/OS (logo)
i5/OS
IBM eServer
IBM (logo)
IBM
IBM zEnterprise System
IMS
InfiniBand
IP PrintWay
IPDS
iSeries
LANDP

Language Environment
MQSeries
MVS
NetView
OMEGAMON
Open Power
OpenPower
Operating System/2
Operating System/400
OS/2
OS/390
OS/400
Parallel Sysplex
POWER
POWER7
PowerVM
PR/SM
pSeries
RACF

Rational Suite
Rational
Redbooks
Redbooks (logo)
Sysplex Timer
System i5
System p5
System x
System z
System z9
System z10
Tivoli (logo)
Tivoli
VTAM
WebSphere
xSeries
z9
z10 BC
z10 EC

zEnterprise
zSeries
z/Architecture
z/OS
z/VM
z/VSE

* All other products may be

trademarks or registered
trademarks of their
respective companies.

The following terms are trademarks or registered trademarks of International Business Machines Corporation in the United States or other countries or both:
Adobe, the Adobe logo, PostScript, and the PostScript logo are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States, and/or other countries.
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Microsoft, Windows, Windows NT, and the Windows logo are trademarks of Microsoft Corporation in the United States, other countries, or both.
InfiniBand is a trademark and service mark of the InfiniBand Trade Association.
Intel, Intel logo, Intel Inside, Intel Inside logo, Intel Centrino, Intel Centrino logo, Celeron, Intel Xeon, Intel SpeedStep, Itanium, and Pentium are trademarks or registered trademarks of Intel
Corporation or its subsidiaries in the United States and other countries.
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IT Infrastructure Library is a registered trademark of the Central Computer and Telecommunications Agency, which is now part of the Office of Government Commerce.
Notes:
Performance is in Internal Throughput Rate (ITR) ratio based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput that any
user will experience will vary depending upon considerations such as the amount of multiprogramming in the user's job stream, the I/O configuration, the storage configuration, and the workload
processed. Therefore, no assurance can be given that an individual user will achieve throughput improvements equivalent to the performance ratios stated here.
IBM hardware products are manufactured from new parts, or new and serviceable used parts. Regardless, our warranty terms apply.
All customer examples cited or described in this presentation are presented as illustrations of the manner in which some customers have used IBM products and the results they may have
achieved. Actual environmental costs and performance characteristics will vary depending on individual customer configurations and conditions.
This publication was produced in the United States. IBM may not offer the products, services or features discussed in this document in other countries, and the information may be subject to
change without notice. Consult your local IBM business contact for information on the product or services available in your area.
All statements regarding IBM's future direction and intent are subject to change or withdrawal without notice, and represent goals and objectives only.
Information about non-IBM products is obtained from the manufacturers of those products or their published announcements. IBM has not tested those products and cannot confirm the
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Prices subject to change without notice. Contact your IBM representative or Business Partner for the most current pricing in your geography.
Refer to www.ibm.com/legal/us for further legal information.

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Agenda

What is CICS Sockets and what is

CICS Sockets Domain?

Introduction to CICS Sockets
Domain

Introduction to CICS Sockets (aka
IP sockets)

What is hot and sizzling in the
z/OS IP community?

Note:
CICS Sockets Domain is part
of CICS TS and provides
support for HTTP(S), IIOP(S),
IPIC, and ECI access to CICS
transactions.
CICS Sockets is part of the
z/OS Communications Server
and provides generalized
sockets programming
interface support for CICS
transactions.

CICS IP activity monitoring from

the TCP/IP side
Disclaimer: All statements regarding IBM future direction or intent, including current product plans, are subject to
change or withdrawal without notice and represent goals and objectives only. All information is provided for
informational purposes only, on an as is basis, without warranty of any kind.
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2011 SHARE and IBM Corporation

TCP/IP for CICS Systems Programmers

What is CICS Sockets and what is

CICS Sockets Domain?

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CICS Sockets (aka IP Sockets) vs. CICS Sockets Domain

A CICS Sockets transaction has direct access to
the TCP/IP socket and can issue native sockets
calls to receive and send data over the socket.
IPv6 is supported. Secure connections via AT-TLS.
No restrictions in application layer protocol.

A CICS Sockets Domain transaction does not have direct access

to the socket, but communicates with CICS Sockets Domain
services to receive a request and to send a reply over a socket.
Secure connections are supported via native system SSL calls.
Restricted to supported application layer protocols.

CICS Application Program

Application-layer
protocol is
transparent to the
enhanced CICS
Sockets listener.
These services
are based on the
Sockets Extended
sockets APIs
(provided by
Communications
server)
Inbound and
outbound
connections,
UDP and
multicast
support, IPv4
and IPv6

CICS Sockets APIs and

traditional CICS APIs
CICS
Sockets
generic
Listener

CICS
Sockets
generic
Listener

Traditional CICS APIs (COMMAREA)

CICS
CICS
Web CICS REGION
IIOP
Listener
Listener

ECI over
TCP/IP
Listener

USER
Listener

ICIP
Listener

CICS Sockets (TRUE

and MVS subtasks or
OTE)

CICS Sockets Domain integral part of CICS TS

EZASOKET

C/C++/Callable BPX Sockets

A conversational
model - or a
request/reply model

Primarily a
request/reply
model

TCPIPServices
represent the
"application" layer
protocols
supported by CICS
Sockets Domain
These services are
based on the UNIX
System Services
C/C++ sockets API
(provided by
Language
Environment) and
the UNIX System
Services callable
APIs

Inbound connections to
supported application
protocols and outbound
from all except ECI.

The network
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2011 SHARE and IBM Corporation

z/OS Sockets programming interfaces

Sockets application programs or subsystems utilizing sockets APIs

CICS Sockets
transaction

P
a
s
c
a
l

R
e
x
x

C
I
C
S

C
a
l
l

EZASOKET
EZASMI

A
S
M
M
A
C
R
O

X
T
I

R
P
C

R
P
C

RFC
1006

SUN
3.9

NCS

X
W
I
N

S
N
M
P

X
T
I

R
P
C

R
P
C

X11
R4

DPI
1.2

XPG
4.2

SUN
4.0

DCE

TCP/IP provided C sockets API

CICS Sockets
Domain

X
W
I
N

S
N
M
P

X11
R6

DPI
2.0

LE provided C/C++ sockets API

UNIX Systems Services provided callable BPX sockets API

UNIX Systems Services provided Logical File System (LFS)

UNIX Systems Services and TCP/IP provided Physical File Systems (PFS) - AF_INET and AF_INET6

TCP/IP provided TCP/IP protocol stack

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An attempt at a comparison
Attribute

CICS Sockets

CICS Sockets Domain

Ease of use from a programmer perspective

Easy if you are a sockets programmer, otherwise

very difficult

Easy if you are a CICS programmer

Development productivity

Low to medium

Very high if one of the CICS Sockets Domain

application layer protocols can be used

Application layer protocol flexibility (message

formats, code pages, interaction model, error
processing, etc.)

Very high - this is the main reason for using CICS

Sockets instead of CICS Sockets Domain the
user protocol needed is unique and not
supported by CICS Sockets Domain

Low

Sysplex CICS transaction routing

Limited to CICS regions in an LPAR (sharing a

TCP/IP stack)

No GIVE/TAKE Socket support, but DPL can be

used across a Sysplex. Response must be sent
from same CICS region into which the request
arrived

IPv6 support

Yes

Yes from CICS TS 4.1

Web services support (SOAP, XML)

No specific support

Yes

Secure connections

Yes (via AT-TLS)

Yes (via native system SSL usage)

OTE support

Yes

Yes generally supported with a few exceptions

Application control over socket options in use

(KEEPALIVE, TCP_NODELAY, etc.)

Yes

No

CICS as a client (outbound connections)

Yes

Yes for all services except ECI

Support for connectionless sockets (UDP

including multicast)

Yes

No

Management (configuration), trace/debug, and

monitoring integral part of CICS

No

Yes

Standard client support

No

Yes (browsers, IIOP, etc.)

Connection persistence

Somewhat complicated requires use of an

iterative server design or home-written listener

Yes

Cost of high-volume transaction processing

Perceived lower

Perceived higher

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TCP/IP Considerations for the CICS Systems Programmer

Introduction to CICS Sockets

Domain

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Explanation of a few of the TCPIPService options

OVERTYPE TO MODIFY
CEDA ALter TCpipservice( HTTP
TCpipservice
: HTTP
GROup
: SOCKETS
DEscription ==> ABC HTTP SERVER
Urm
==> DFHWBAAX
POrtnumber
==> 05081
STatus
==> Open
PROtocol
==> Http
TRansaction ==> CWXN
Backlog
==> 00020
TSqprefix
==>
Ipaddress
==>
SOcketclose ==> No
Maxdatalen
==> 000032
SECURITY
SSl
==> No
CErtificate ==>

CICS RELEASE = 0650

)

1-65535
Open | Closed
IIop | Http | Eci | User | IPic
0-32767

No | 0-240000 (HHMMSS)
3-524288
Yes | No | Clientauth

When a client connects to your service, it is according to the

underlying application protocol expected to send a request
for the service to process. If the client is in error and
doesn't send any input data after having connected, how
long should your service wait before it closes the
connection down?
Leave this at No if you want to use persistent connections!

Page 10

The TCP/IP port your

service will operate
on - value should be
coordinated with your
TCP/IP systems
programmer to have
him/her reserve that
port in the TCP/IP
profile for this
purpose only
(through port
reservation or RACF
SERVAUTH resource
definitions)

IP address is used to
turn your service into a
bind-specific server only servicing
connection requests
that are received for this
local IP address.

Backlog is used to specify the maximum

number of connections waiting in TCP/IP to
be serviced by your service. If the backlog
queue is full, then new connection requests
will be rejected until the backlog queue falls
below this value again. This has nothing to
do with how many concurrent connections
your service can process at any point in time!
Note: Make sure your TCP/IP systems
programmer has specified an SOMAXCONN
value that supports the maximum backlog
you want/need!
2011 SHARE and IBM Corporation

How do you make your CICS Sockets Domain services bind-specific?

There are two ways you can do it:
1. Specify the local IP address to bind to when defining your TCPIP service:
OVERTYPE TO MODIFY
CEDA ALter TCpipservice( HTTP
TCpipservice
: HTTP
GROup
: SOCKETS
DEscription ==> ABC HTTP SERVER
Urm
==> DFHWBAAX
POrtnumber
==> 05081
STatus
==> Open
PROtocol
==> Http
TRansaction ==> CWXN
Backlog
==> 00020
TSqprefix
==>
Ipaddress
==> 9.42.104.161
SOcketclose ==> No
Maxdatalen
==> 000032
SECURITY
SSl
==> No
CErtificate ==>

2.

CICS RELEASE = 0650

)

1-65535
Open | Closed
IIop | Http | Eci | User | IPic
0-32767
No | 0-240000 (HHMMSS)
3-524288
Yes | No | Clientauth

Or have the TCP/IP systems programmer control it in the TCP/IP configuration data set (the
TCP/IP Profile)
PORT
5081 TCP IMWEBSRV BIND 9.42.104.161 ; z/OS HTTP server
5081 TCP CICSTS32 BIND 9.42.105.45 ; CICS HTTP service

It might be best to let TCP/IP systems programmer control it - by leaving the field empty in the CEDA panel or enter the IP address as 0.0.0.0

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How do you decide which IP address your server is listening on?

 The easiest way is to use the netstat command from either TSO or the UNIX shell (or the MVS console).
I have noticed that the CEMT Q TCPIPS command sometimes display the wrong IP address
TSO: ALLCONN APPLDATA TCP TCPCS ( CLI

CICSTS32

MVS TCP/IP NETSTAT CS V1R11

TCPIP Name: TCPCS
User Id Conn
State
------- -------CICSTS32 000000A4 Listen
Local Socket:
9.42.105.45..5081
Foreign Socket: 0.0.0.0..0
Application Data: DFHICICS1A CWXNHTTP
HTTP
CICSTS32 00000045 Listen
Local Socket:
0.0.0.0..5082
Foreign Socket: 0.0.0.0..0
Application Data: DFHICICS1A CIEPECI
ECI
CICSTS32 00000047 Listen
Local Socket:
0.0.0.0..5083
Foreign Socket: 0.0.0.0..0
Application Data: DFHICICS1A CIRRIIOP
IIOP
CICSTS32 00000048 Listen
Local Socket:
0.0.0.0..5084
Foreign Socket: 0.0.0.0..0
Application Data: DFHICICS1A CISSIPIC
IPIC

13:22:46

ABC HTTP

CICS ECI

CICS IIO

CICS IPI

The services you did not make bind-specific - in this example ECI on port 5082, IIOP on port 5083, and IPIC
on port 5084 show up in your netstat display with the local socket IP address as 0.0.0.0.
They will receive connection requests that arrive on any of the IP addresses in the HOME list.
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Establishing stack-affinity for UNIX System Services sockets (CICS

Sockets Domain)
 Affinity for CICS Sockets Domain to
one of more stacks in an LPAR can
be established at an address-space
level, and will be in effect for all CICS
Sockets Domain access from that
address space.
 The simplest way to establish stack
affinity is to add a small job step to
your CICS startup procedure.
Executing PGM=BPXTCAFF
 All CICS Sockets Domain activity
from this address space will only use
the TCPCS TCP/IP stack on this
LPAR
 CICS Sockets activity is made stackaffinity via the TCPADDR keyword
when defining your CICS entry to
CICS Sockets (EZACICD macro or
EZAC transaction)
Page 13

//DFHSTART PROC START='AUTO',

// INDEX1='DCICS.CICSTS32',
// INDEX2='CICSTS.V3R2M0.CICS',
// REGNAM='1A',
// REG='64M',
// DUMPTR='YES',
// RUNCICS='YES',
// OUTC='*',
// SIP=T,
// TCPHLQ='CS390.CS1B.PRD'
//*
//* Set affinity to TCPCS stack on mvs098
//*
//AFFINITY EXEC PGM=BPXTCAFF,PARM='TCPCS'
//*
........
//CICS
EXEC PGM=DFHSIP,REGION=&REG,TIME=1440,
// COND=(1,NE,CICSCNTL),
// PARM='START=&START,SYSIN'

Note: CICS Sockets stack-affinity is determined via

CICS Sockets definitions in the CICS entry in the
CICS Sockets configuration data set.

2011 SHARE and IBM Corporation

TCP/IP for CICS Systems Programmers

Introduction to CICS Sockets (aka

IP sockets)

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CICS Sockets overview

 Multiple listeners each instance
separately configurable

 Enhanced listener has no

requirements on client input data

 Multiple listeners in many CICS

regions can share listener port number
 User ID security

CICS Sockets is a component of the

Communications Server for z/OS, not CICS
TS itself.
It is a general-purpose sockets
programming API to be used by CICS
application programmers for implementing
native (low-level) sockets communication in
z/OS CICS transaction programs.

 SSL/TLS support by means of ATTLS

 Configuration file and transaction
(EZAC)
 Operations transaction to start/stop
individual listeners (EZAO)
 PLT-enabled start and termination
 Reusable subtasks

 UDP and multicast support

Page 15

TCP/IP
Stack

LST2
TRNA

T
R
U
E

EZAO
EZAC

 OTE enabled
 IPv6 support

Pool of reusable
socket subtasks

LST1

PLTx
Build
EZACICD

Conf.
file

CICS/ESA or
CICS TS Region

CICS Sockets is implemented as an External

Resource Manager in CICS (using a Task
Related User Exit - a TRUE).
2011 SHARE and IBM Corporation

CICS entry in CICS Sockets configuration file - EZAC transaction

EZAC,ALTer,CICS

APPLID = CICS1A

Overtype to Enter
APPLID
TCPADDR
NTASKS
DPRTY
CACHMIN
CACHMAX
CACHRES
ERRORTD
SMSGSUP
TERMLIM
TRACE
OTE
TCBLIM
PLTSDI
APPLDAT

PF 3 END

===>
===>
===>
===>
===>
===>
===>
===>
===>
===>
===>
===>
===>
===>
===>

CICS1A
TCPCS
100
010
010
020
005
CSMT
NO
000
YES
NO
00000
NO
YES

APPLID of CICS System

Name of TCP Address Space
Number of Reusable Tasks
DPRTY Value for ATTACH
Minimum Refresh Time for Cache
Maximum Refresh Time for Cache
Maximum Number of Resolvers
TD Queue for Error Messages
Suppress Task Started Messages
Subtask Termination Limit
Trace CICS Sockets
Open Transaction Environment
Number of Open API TCBs
CICS PLT Shutdown Immediately
Register Application Data

CICS Sockets
always uses
one TCP/IP
stack only which one is
specified with
the TCPADDR
keyword.

12 CNCL

To get APPLDATA in Netstat for CICS Sockets Sockets, you must specify YES to APPLDAT on the CICS entry
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2011 SHARE and IBM Corporation

Listener entry in CICS Sockets configuration file - EZAC transaction screen 1 of 2

EZAC,ALTer,LISTENER (standard listener.

screen 1 of 2)

APPLID = CICS1A

Overtype to Enter
APPLID
TRANID
PORT
AF
IMMEDIATE
BACKLOG
NUMSOCK
ACCTIME
GIVTIME
REATIME
RTYTIME
LAPPLD

===>
===>
===>
===>
===>
===>
===>
===>
===>
===>
===>
===>

CICS1A
CSKL
03001
INET
YES
040
100
060
000
000
015
INHERIT

APPLID of CICS System

Transaction Name of Listener
Port Number of Listener
Listener Address Family
Immediate Startup
Yes|No
Backlog Value for Listener
Number of Sockets in Listener
Timeout Value for ACCEPT
Timeout Value for GIVESOCKET
Timeout Value for READ
Stack Connection Retry Time
Register Application Data

You specify if
the listener is
an IPv4 or an
IPv6 listener
(INET or INET6)

Verify parameters, press PF8 to go to screen 2

or ENTER if finished making changes
PF 3 END

8 NEXT

12 CNCL

To get APPLDATA in Netstat for this listener, specify YES or INHERIT (inherit from the CICS entry)
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Listener entry in CICS Sockets configuration file - EZAC transaction screen 2 of 2

EZAC,ALTer,LISTENER (standard listener.

screen 2 of 2)

APPLID = CICS1A

Overtype to Enter

MINMSGL
TRANTRN
TRANUSR
SECEXIT
GETTID
USERID

===>
===>
===>
===>
===>
===>

004
NO
NO
NO

Minimum Message Length

Translate TRNID
Yes|No
Translate User Data Yes|No
Name of Security Exit
Get AT-TLS ID (YES|NO)
Listener User ID

Verify parameters, press PF7 to go back to screen 1

or ENTER if finished making changes
PF 3 END

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2011 SHARE and IBM Corporation

CICS Sockets program categories in CICS

Remote
Sockets
Server

Connect
Send/Receive

CICS Task
Non-socket
transaction
initiation - 3270
terminal input,
IC, batch input,
etc.

Sockets Client
CICS Task

Remote
Sockets
Client

Connect
Send/Receive

Iterative Socket Server

Started via PLT
or via EZAO
transaction.

CICS Task
Connect
Remote
Sockets
Client

Send TRM

Sockets Listener
(CSKL)
CICS Task

Send/Receive

Pass the socket

EXEC
CICS
START

Concurrent Sockets
Child Server
Concurrent Sockets Server

CICS Region

TRM: Transaction Request Message

Please note that use of the Enhanced Sockets Listener removes the requirement for the client sending a transaction request
message - in reality removing any requirements from the CICS Sockets infrastructure on the application-level protocol between
the client and the server running in CICS.
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Concurrent CICS Sockets server - overview

Listener

Client
Connect to listener
[Send TRM]

Do Forever
Accept connection request
[Read TRM from client]
[Call security exit]
Givesocket
EXEC CICS START passing TIM
If errors, send err message
end

Transaction Initiation Message

[Read OK/Error Message]

Listener socket descriptor number

Listener TCP/IP ID
TRM user data
Remote client socket address

Send Request
Read Reply
Close socket

Child Server
EXEC CICS Retrieve of TIM
Takesocket
[Send OK Message to client]
Read request data from client
Process request
Send reply to client
Close socket

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2011 SHARE and IBM Corporation

Client Listener interactions

CICS Sockets configuration

CICS Sockets
Listener port1

CICS Transaction
TRA1

Application input

CICS Sockets
Listener port2
Associate to TRA2

CICS Transaction
TRA2

Application input

CICS Sockets
Listener port3
User exit to assign
transaction code

CICS Transaction
TRA3

Application input

TRA1,user1/pwd1

TCP/IP
Network

CICS Region

 Three ways to launch CICS transactions:

Via a Transaction Request Message standard listener
Via a listener configuration option to associate listener instance (and port) with one specific CICS
transaction code
Via the listener security user exit, driven by the listener
 With the last two options, data may be sent by the client in completely free format.

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2011 SHARE and IBM Corporation

TCP/IP for CICS Systems Programmers

What is hot and sizzling in the z/OS

IP community?

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2011 SHARE and IBM Corporation

Information technology today: Limitations

Information technology today is limited by the technology and architecture
configurations available

Web Servers

SSL/XML
Appliances

System z

Security/Directory
Servers
Application
Servers

Routers
Switches

Firewall
Servers

Caching
Appliances

DS Servers

Business Intelligence
Servers

File/Print
Servers

LAN Servers





Business processes and the applications that support them are becoming more service oriented, modular in their
construction, and integrated.
The components of these services are implemented on a variety of architectures and hosted on heterogeneous IT
infrastructures.
Approaches to managing these infrastructures along the lines of platform architecture boundaries cannot optimize:
alignment of IT with business objectives; responsiveness to change; resource utilization; business resiliency; or overall
cost of ownership.
Customers need a better approach: The ability to manage the IT infrastructure and Business Application as an
integrated whole in a much simplified manner.

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2011 SHARE and IBM Corporation

IBM zEnterprise System Overview

X86 Blades

Power Blades

Optimizers

PR/SM

xHypervisor
xHypervisor
xHypervisor

xHypervisor
xHypervisor
pHypervisor

Future

z/VM

Smart Analytics Optimizer

DataPower

x/Linux
x/Linux
AIX

x/Linux
x/Linux
AIX
x/Linux
x/Linux
AIX

x/Linux
x/Linux

Linux on System x

x/Linux
x/Linux
Linux on System x
x/Linux
x/Linux

Linux on System x

Linux on System z

Linux on System z

Linux on System z

z/OS

z/OS

z/OS

z/OS

System z Hardware Management Console

With Unified Resource Manager

zEnterprise Node

Z CPU, Memory and IO

Support Element (SE)

z196

Blade Center Advanced Management Module (AMM)

zBX

Connecting the pieces with zManager (aka. Unified Resource Manager)!

1

All statements regarding IBM future direction and intent are subject to change or withdrawal without notice, and represents goals and objectives only.

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2011 SHARE and IBM Corporation

IBM zEnterprise node with internal networks

Customer
managed
management
network

zEnterprise Node

HMC

OSM
OSM

Intra Node
Management
Network
(INMN)

TOR
TOR
TOR
TOR

z196
OSX
OSX
OSD

Customer
managed
data
networks
Page 25

Intra
Ensemble
Data Network
(IEDN)

zBX

BladeCenter
rack
2011 SHARE and IBM Corporation

IBM zEnterprise OSA and Network Types

HMC

zEnterprise node
LP1
z/OS

LP2
z/OS

LP3
z/OS

LP5 z/VM

LP4
z/OS

VS1

VS2

VS3

Customer
external
data
network
access
OSA OSD

VS4
z/VM virtual
switch

SE
OSD
OSD

Firewall
F
I
R
E
W
A
L
L

OSX
OSX

OSM
OSM

BC1
Customer
external
data
network

BC2

z196

BC3

TOR
TOR

TOR
TOR
ESM
ESM

ESM
ESM

ESM
ESM

ESM
ESM

ESM
ESM

ESM
ESM

zBX
IEDN may
extend to other
zEnterprise
nodes within an
ensemble

Page 26

Intra
Ensemble
Data Network
(IEDN) OSA
OSX 10 GbE

Intra Node
Management
Network (INMN)
OSA OSM 1 GbE
(1000BaseT)

2011 SHARE and IBM Corporation

Use of multiple VLANs on the IEDN no routing, but application layer gateways
between VLANs
Virtual servers that act as
application layer gateways
have, under zManager
control, access to two VLANs

VLAN3

zEnterprise node
LP1
z/OS

LP2
z/OS

LP3
z/OS

LP5 z/VM

LP4
z/OS

VS1

z/OS IP Filtering
and routing

TOR
TOR

OSX
OSX

ESM
ESM

BC2

ESM
ESM

Customer
external
These nodes should be
data
network configured with forwarding

Page 27

VS3

VS4

SE

OSM
OSM

Application
BC1
layer gateway

ESM
ESM

disabled.
z/OS is by default prevented
from routing between IEDN
VLANs.

VS2

z/VM virtual
switch

OSD
OSD

VLAN1

HMC

z196

Application
BC3
layer gateway

ESM
ESM

ESM
ESM

TOR
TOR

ESM
ESM

zBX

VLAN2

2011 SHARE and IBM Corporation

Sysplex Distributor support for DataPower

z/OS Sysplex
System z CPC2
System z CPC1
LPAR1

LPAR2

LPAR3

LPAR4

CICS

CICS

CICS

CICS

WAS

WAS

WAS

WAS

IMS

IMS

IMS

IMS

DB2

DB2

DB2

DB2

 Introduced in z/OS V1R11

Communications Server
DataPower Support in Firmware 3.8.1

 Allows Sysplex Distributor to load

balance connections to a cluster
of DataPower appliances that
front-end a z/OS Sysplex
environment (Tier 1)
Complements Sysplex Distributor
support for back-end workflows
(DataPower to z/OS Tier 2)

Sysplex Distributor

 Sysplex Distributor and

DataPower communicate over a
control connection

Sysplex Distributor

Web
Service
request
Page 28

Dynamic
Load Balancing
Feedback

Allows SD to have awareness of state

and utilization levels of each
DataPower instance
Facilitates TCP connection
management and use of GRE to
preserve clients IP address visibility to
DataPower

2011 SHARE and IBM Corporation

When do our z/OS customers believe they will need IPv6?

 The majority of z/OS customers do not know
Expectations are that it will be needed slightly earlier on other
platforms than z/OS
 It is time to start thinking, learning, and preparing now !
IPv6 on z/OS

IPv6 on other platforms

100.00

100.00

90.00

90.00

80.00

80.00

70.00

70.00

60.00

60.00

50.00

50.00

40.00

40.00

30.00

30.00

20.00

20.00

10.00

10.00

0.00

0.00
2009 2010

2011 2012

2013 2014

2015 2016

Later than 2016 Do not know

2009 2010

2011 2012

2013 2014

2015 2016 Later than 2016 Do not know

Source: Survey conducted by ENS early 2009 among a selected set of customers (39 responses to this question)
Page 29

2011 SHARE and IBM Corporation

IPv4 address usage since early 1993

 z/OS Communications Server

continues to focus on IPv6
standards currency
US DoD/NIST
IPv6 Forum

Advertised by DNS servers

900
800
700
600
500
400
300
200
100
0
01/1993
07/1993
01/1994
07/1994
01/1995
07/1995
01/1996
07/1996
01/1997
07/1997
01/1998
07/1998
01/1999
07/1999
01/2000
07/2000
01/2001
07/2001
01/2002
07/2002
01/2003
01/2004
07/2004
01/2005
07/2005
01/2006
07/2006
01/2007
07/2007
01/2008
07/2008
01/2009
07/2009
01/2010
07/2010
01/2011

 Projected Regional Internet

Registries (RIR) Unallocated
Address Pool Exhaustion
August 2011

Hosts on the Internet

Number of hosts
in millions

 Projected Internet Assigned

Numbers Authority (IANA)
Unallocated Address Pool
Exhaustion
Happened Feb 1, 2011

Year
What is the upper practical limit (the ultimate pain threshold) for number of assigned IPv4
addresses? Some predictions said 250,000,000 (250 million), others go up to 1,000,000,000
(one billion or one milliard).
Source: https://www.isc.org/solutions/survey
Source: http://www.potaroo.net/tools/ipv4/index.html
Source: http://penrose.uk6x.com/

If you want to stay in business after 2011/2012, youd better start paying attention!
Do not worry too much; the sky isnt falling IPv4 and IPv6 will coexist for many years to come.
Your applications need to be able to use both. If you write directly to the TCP/IP sockets layer, you
need to start changing those applications.
Page 30

2011 SHARE and IBM Corporation

How the IPv4 address space is managed

IPv4 Address Pool Status per
Fenruary 2011

IANA
Internet
Assigned
Numbers
Authority

The IPv4 Address Space

Allocated

Un-allocated
IPv4 Unicast
pool

Reserved

Reserved
Un-allocated
Allocated

Address allocation to RIRs

RIR
Regional Internet Registries
(RIRs): AFRINIC, APNIC,
ARIN, LACNIC, RIPENCC

LRIR

Internet Service
Providers (ISPs)

Local Internet
Registries
(LRIRs)

Companies or
"consumers"

The IANA pool

of un-allocated
addresses was
exhausted in
February 2011

Source: "IPv4 Address Report" - http://www.potaroo.net/tools/ipv4/

Page 31

2011 SHARE and IBM Corporation

Is Doomsday approaching?
http://www.potaroo.net/tools/ipv4/index.html

This is
less than
six
months
from
now!!!!
z/OS Communications Server keeps the
pace, adding required new IPv6 support
Page 32

2011 SHARE and IBM Corporation

Tracking RIR allocations

http://www.potaroo.net/tools/ipv4/index.html
Page 33

2011 SHARE and IBM Corporation

So - what is IPv6?
 IPv6 is an evolution of the current version of IP, which is known as IPv4
Work on new IETF standard started in early 90's
Not backward compatible, but migration techniques defined
 Today's IPv4 has 32 bit addresses
Theoretical limit is around 4 billion addresses
Due to IPv4 address assignment structure and policies, the practical
limit is less than 1 billion useable global addresses

IPv4 Address:
9.67.122.66

 IPv6 provides almost unlimited number of addresses

IPv6 addresses are 128 bits
IPv6 Address:
No practical limit on global addressability
2001:0DB8:4545:2::09FF:FEF7:62DC
Enough address space to meet all imaginable
needs for a while
More addresses cannot be retrofitted into IPv4
 Other improvements important, but to some extent secondary:
Facilities for automatic configuration
Improved support for site renumbering
End to end IP security
Mobility with route optimization (important for wireless)
Miscellaneous improvements aimed at improving router performance
Page 34

2011 SHARE and IBM Corporation

z/OS TCP/IP is a dual-mode TCP/IP stack

 A dual-mode (or dual-stack)
TCP/IP implementation supports
both IPv4 and IPv6 interfaces
and both old AF_INET and
new AF_INET6 applications.

Application migration
IPv4 and IPv6 application

 For AF_INET6 applications,

the common TCP or UDP
transport layer determines per
communication partner if the
partner is an IPv4 or an IPv6
partner - and chooses IPv4 or
IPv6 networking layer component
based on that.

AF_INET PFS

AF_INET6 PFS

IPv6 Raw
Transport

 The dual-mode TCP/IP

implementation is a key
technology for IPv4 and IPv6
coexistence in an internet.

IPv4-only application

Common TCP and UDP Transport

IPv6
NeD
MLD
Stateless
autoconfig

ICMPv6

QoS
(IDS)
IPSec

IPv4 Raw
Transport

IPv4

QoS
IDS
IPSec

ARP

IGMP

ICMP

Common DLC Functions

IPv4 DLCs

IPv6 DLCs

z/OS TCP/IP

Network Interface
Adapter

IPv4 and IPv6 packets on the same LAN

over the same OSA port

 Raw applications make the determination themselves when they choose IPv4 or IPv6 raw
transport.
Page 35

2011 SHARE and IBM Corporation

IPv6 and CICS

 CICS TS 4.1 IPv6 enables the CICS Sockets Domain services
 CICS Sockets was IPv6 enabled a few years ago
 CICS transaction Gateway for z/OS is IPv6 enabled

Page 36

2011 SHARE and IBM Corporation

Enable a CICS sockets listener for IPv6 connectivity

INET6 instead of INET
EZAC,DISplay,LISTENER (standard listener.

APPLID
TRANID
PORT
AF
IMMEDIATE
BACKLOG
NUMSOCK
ACCTIME
GIVTIME
REATIME
RTYTIME
LAPPLD

===>
===>
===>
===>
===>
===>
===>
===>
===>
===>
===>
===>

CICS1A
LSN0
06000
INET6
YES
020
050
060
000
000
015
YES

screen 1 of 2)

APPLID = CICS1A

APPLID of CICS System

Transaction Name of Listener
Port Number of Listener
Listener Address Family
Immediate Startup
Yes|No
Backlog Value for Listener
Number of Sockets in Listener
Timeout Value for ACCEPT
Timeout Value for GIVESOCKET
Timeout Value for READ
Stack Connection Retry Time
Register Application Data

Verify parameters, press PF8 to go to screen 2

Press ENTER or PF3 to exit
PF 3 END
Page 37

8 NEXT

12 CNCL
2011 SHARE and IBM Corporation

IPv6-enabled transaction initiation message

*---------------------------------------------------------------*
* Transaction Initiation Message from CICS listener
*
*---------------------------------------------------------------*
01 CICS-listener-TIM.
05 give-take-sd
pic 9(8) Binary value zero.
05 lstn-asname
pic x(8).
05 lstn-subtask
pic x(8).
05 client-in-data
pic x(35).
05 lstn-ote
pic x(1).
05 sockaddr-in.
10 sin-family
pic 9(4) Binary.
10 sock-data
pic x(26).
10 sock-sin-data redefines sock-data.
15 sock-sin-port
pic 9(4) Binary.
15 sock-sin-addr
pic 9(8) Binary.
15 filler
pic x(20).
10 sock-sin6-data redefines sock-data.
15 sock-sin6-port
pic 9(4) Binary.
15 sock-sin6-flowinfo
pic 9(8) Binary.
15 sock-sin6-addr
pic x(16).
15 sock-sin6-scope
pic 9(8) Binary.
05 filler
pic x(68).
05 client-indata2-len
pic 9(4) Binary.
05 client-indata2
pic x(1).

Page 38

2011 SHARE and IBM Corporation

IPv6 enabled CICS Sockets child server transaction

*---------------------------------------------------------------*
* Receive TIM from the CICS Listener.
*
*---------------------------------------------------------------*
move 160 to cleng.
exec cics retrieve
into(CICS-listener-TIM)
length(cleng)
end-exec.
if sin-family = 19 then
move sin-family to ntop-family
move 45 to addrlen
Call 'EZASOKET' using soket-ntop
ntop-family
sock-sin6-addr
startup-sin-addr
addrlen
errno
retcode
if retcode < 0 then
move 'Ntop failed' to ezaerror-text
perform write-ezaerror-msg thru
write-ezaerror-msg-exit
end-if
End-if
TPICICSS Startup parms:
Page 39

01 CICSTS32

Receive the TIM from the

listener specify a length that is
at least
Family=2 means IPv4,
Family=19 means IPv6.
NTOP convert binary IPv6
address to printable text.

In this case, the client is really

an IPv4 client.

00043L 0019 01135 ::FFFF:9.42.104.232

2011 SHARE and IBM Corporation

Sysplex Distributor hot standby support

 Have a single target server to receive all new connection
requests
While other target servers are active but not receiving
any new connection requests
Automatically route traffic to a backup target server
when the active target server is not available
 Enable using a new HOTSTANDBY distribution method
One preferred target
AUTOSWITCHBACK option - switch to the
preferred target if it becomes available
No auto switch back if reason for original switch
was health problems
Use a V TCPIP Quiesce and Resume sequence
One or more backup targets ranked in order of
preference
A target is not available when:
Not ready OR
Route to target is inactive OR
If HEALTHSWITCH option configured target is
not healthy when
TSR = 0% OR
Abnormal terminations = 1000 OR
Server reported Health = 0%
Page 40

DB2 Data
sharing
group
DB2

DB2

Preferred
Target
server

Backup
Target
server

Sysplex
Distributor

VIPADEFINE DVIPA1
VIPADISTRIBUTE DISTMETHOD HOTSTANDBY
AUTOSWITCHBACK HEALTHSWITCH
DVIPA1 PORT nnnn
DESTIP XCF1 PREFERRED
DESTIP XCF2 BACKUP 50
DESTIP XCF3 BACKUP 100
2011 SHARE and IBM Corporation

Performance improvements for fast local sockets

 Fast local sockets (FLS)

 Faster local sockets (Turbo FLS)

Optimized path through TCP/IP

Bypassing the IP layer

Bypasses processing on both sending and

receiving side

Data placed on TCP send queue

Data is then moved to TCP receive queue
ACKs built and sent from receive side

Used when socket end-points are on same

stack
Dynamic; no configuration required

Data no longer placed on TCP send queue

Data is placed directly onto receive queue bypassing
TCP inbound processing
Data no longer ACKed

Enabled automatically; no configuration changes

Reverts to fast local sockets if packet trace or AT-TLS

is enabled
No impact for data trace

Application A

Application B

Application A

Application B

Send()

Recv()

Send()

Recv()

Sockets layer
TCP/UDP/RAW

Faster local sockets

Sockets layer

Fast local sockets

TCP/UDP/RAW

IP layer

IP layer

Normal path
Device layer

Page 41

Device layer

2011 SHARE and IBM Corporation

TCP/IP for CICS Systems Programmers

CICS Sockets monitoring from

the TCP/IP side

Page 42

2011 SHARE and IBM Corporation

APPLDATA CONNECT (Client socket in CICS)

Page 43

2011 SHARE and IBM Corporation

APPLDATA GIVESOCKET (Socket given by listener to child server)

Page 44

2011 SHARE and IBM Corporation

APPLDATA TAKESOCKET (Socket taken by child server)

Page 45

2011 SHARE and IBM Corporation

APPLDATA LISTEN (Listener socket)

Page 46

2011 SHARE and IBM Corporation

The IBM z/OS Communications Server Network Utility Assistant

 There is a new tool available for download from the z/OS Communications Server web
pages:
http://www-01.ibm.com/support/docview.wss?uid=swg24029203
 The IBM z/OS
Communications Server
Network Utility Assistant
tool is a TSO/ISPF front-end
to the z/OS Communications
Server TSO NETSTAT
line-mode command.

*--------------------- z/OS V1R12 CS TCP/IP NETSTAT --------------------------*

Command ===>
Select a report option by number or name ==>
1
6
11
16
21
26
90

ALL
CONFig
PORTList
CACHinfo
VDPT
DROP
TN3270

2
7
12
17
22
27
91

ALLConn
CONN
ROUTe
SLAP
IDS
TTLS
CICSsock

3
8
13
18
23
28
92

ARp
DEVlinks
SOCKets
VIPADYn
STATS
RESCache
FTP

4
9
14
19
24
29
93

BYTEInfo
Gate
TELnet
VIPADCFG
ND
DEFADDRT
CICSTS

5
10
15
20
25

CLients
HOme
UP
VCRT
SRCIP

Enter optional command modifiers and selection filters:

Do you want to specify optional command modifiers
Do you want to specify optional selection filters

==> N
==> N

(Y/N)
(Y/N)

Enter optional TCP/IP stack name and general options:

Stack name
Interval
Report format
Excl. TN3270
Netstat debug
EZANS
debug

==>
==>
==>
==>
==>
==>

TCPCS
5
LONG
N
N
N

Leave blank for default stack

Seconds for interval display
(Short/Long) Leave blank for stack-default
(Y/N) Reply Y to exclude TN3270 connections
(Y/N) Reply Y to see debug messages from Netstat
(Y/N) Reply Y to see debug messages from EZANS

Enter required arguments for ARP and DROP commands:

ARP address
Conn id

Page 47

==> ALL
==>

ARP (specify an IPv4 address or ALL)

DROP (Specify connection ID to drop)

2011 SHARE and IBM Corporation

What you can do with APPLDATA in Netstat CICS Sockets

 APPLDATA is identification data a sockets application can associate with a sockets end point.
 CICS Sockets uses that feature to associate CICS-specific identification data with sockets that are
used by the CICS Sockets.
 APPLDATA can be displayed with netstat, it is included in TCP/IP SMF records, and in the Network
Management API.

*-------------------- MVS TCP/IP NETSTAT CS z/OS V1R10 -----------------------*

Command ===>
Please enter optional selection criteria for CICS Sockets connection overview or press END to continue without any selection criteria.
Remote IP address
Local IP address
CICS Sockets server port
CICS address space name
CICS user ID
CICS transaction code
CICS task number
CICS system name
CICS Sockets type

==>
==>
==>
==>
==>
==>
==>
==>
==>

CICS listener server port

CICS address space that owns socket
CICS assigned user ID
CICS transaction identifier
CICS internal task number
CICS name transaction assigned to
Listener, Given, Taken, Connect

If you want a display of all your CICS Socket connections, leave all
selection fields above blank.
Page 48

2011 SHARE and IBM Corporation

APPLDATA socket states

Listener transaction
Listener
socket
Connect()

Remote
client

Child server transaction

LISTENER

TakeSocket()
Connected
Socket (taken)

Accept()

TAKEN

Connected
Socket (given)
GiveSocket()

GIVEN
Connected
Socket (given)

CONNECT
Remote
server

Connected
Socket

CICS
Page 49

2011 SHARE and IBM Corporation

CICS Sockets customized netstat displays

 The socket type may be:
Listener
listener socket
Given
Given by the listener, but not yet taken by the child server
Taken
taken and currently owned by the child server
Connect
outbound connection
*-------------------- MVS TCP/IP NETSTAT CS z/OS V1R10 ------- Row 1 to 3 of 3
Command ===>
Scroll ===> PAGE
CICS Sockets overview
Line command: S Connection summary, P Ping remote address,
L Listener details, and D Drop connection
Socket
CICS
CICS
S ConnID status
ASName
ID
- ------ -------- -------- ---0000F7 Listen
CICSTS32 CICT
0000F8 Listen
CICSTS32 CICT
0000FD Establsh CICSTS32 CICT
*******************************
Page 50

Socket
CICS
type
Port
-------- ----Listener 3001
Listener 6000
Taken
6000
Bottom of data

CICS
CICS Tran
TaskNo Tran UserID
------- ---- -------0000131 CSKL CICSUSER
0000132 LSN0 CICSUSER
0000134 SRV1 CICSUSER
********************************
2011 SHARE and IBM Corporation

CICS Sockets customized netstat displays socket details

*-------------------- MVS TCP/IP NETSTAT CS z/OS V1R11 -----------------------*
Command ===>
Details for CICS Sockets connection ID: 0000058E
Local address . .
Foreign address .
Connection status
Last touched . .
Last touched . .

.:
.:
.:
.:
.:

9.42.105.45..6000
9.42.104.161..1127
Establsh
23:17:35 (UTC)
18:17:35 (LCL) Idle time . . . . .: 00:00:13

Security information
ATTLS protected .
FIPS 140 . . . .
SSL/TLS protocol.
Cipersuite. . . .

.:
.:
.:
.:

No
N/A
N/A
N/A

Certificate userID.: N/A

Mapping type. . . .: N/A

CICSTS32
SRV1
CICSUSER
6000

CICS system name. .: CICT

CICS task number. .: 0000044
CICS Sockets type .: Taken

4
5
0
1,048,160
N/A
0
258.00
No

TCP segments out. .:

TCP bytes out . . .:
Receive data queued:
Current recv window:
Max segment size. .:
Duplicate ACKs . .:
TCP RTT variance .:
KEEPALIVE set . . .:

CICS information
CICS
CICS
CICS
CICS

address space :
tran code. . .:
tran user ID .:
local port . .:

TCP flow information

TCP segments in . .:
TCP bytes in . . .:
Send data queued. .:
Current send window:
Congestion window .:
Total retransmits .:
TCP RTT (msec) . .:
TCP NODELAY set . .:

Page 51

2
50
0
131,067
8,940
0
844.00
No
2011 SHARE and IBM Corporation

What you can do with APPLDATA in Netstat CICS Sockets Domain

 CICS TS 3.2 also uses the APPLDATA feature to associate CICS-specific identification
data with sockets that are used by the CICS Sockets Domain.
 APPLDATA can be displayed with netstat, it is included in TCP/IP SMF records, and in
the Network Management API.
*-------------------- MVS TCP/IP NETSTAT CS z/OS V1R10 -----------------------*
Command ===>
Please enter optional selection criteria for CICS sockets domain sockets or press END to continue without any selection criteria.
Remote IP address
Local IP address
Local port number
Connection direction
Owning CICS APPLID
CICS transaction ID
CICS network protocol
Listener service name
IPCONN name
APPLID of partner system

==>
==>
==>
==>
==>
==>
==>
==>
==>
==>

TCP port number (Listening port)

In (listen / accept), Out (connect)
CICS application ID that owns socket
CICS trans that created socket
ECI,HTTP,IIOP,IPIC, or USER
Service name if listening socket
IPCONN name
Partner APPLID for connected IPIC

If you want a display of all your CICS sockets domain sockets,

leave the selection fields above blank.
Page 52

2011 SHARE and IBM Corporation

CICS Sockets Domain customized netstat displays

*-------------------- MVS TCP/IP NETSTAT CS z/OS V1R10 ------- Row 1 to 5 of 5

Command ===>
Scroll ===> PAGE
CICS Sockets domain overview
Line command: S Connection summary, P Ping remote IP address,
L Listener information, and D Drop connection
Socket
CICS
CICS
Dir Tran Proto- Service IPCONN
Partner
S ConnID status
ASName
APPLID
code col
name
name
APPLID
- ------ -------- -------- -------- --- ---- ------ -------- -------- -------000045 Listen
CICSTS32 CICS1A
In CIEP ECI
ECI
N/A
N/A
000047 Listen
CICSTS32 CICS1A
In CIRR IIOP
IIOP
N/A
N/A
000048 Listen
CICSTS32 CICS1A
In CISS IPIC
IPIC
N/A
N/A
0000A4 Listen
CICSTS32 CICS1A
In CWXN HTTP
HTTP
N/A
N/A
000123 Establsh CICSTS32 CICS1A
In CWXN HTTP
HTTP
N/A
N/A
******************************* Bottom of data ********************************

Page 53

2011 SHARE and IBM Corporation

CICS Sockets Domain customized netstat displays socket details

*-------------------- MVS TCP/IP NETSTAT CS z/OS V1R10 -----------------------*
Command ===>
Details for CICS Sockets domain connection ID: 00000123
Local address . .
Foreign address .
Connection status
Last touched . .
Last touched . .

.:
.:
.:
.:
.:

9.42.105.45..5081
9.65.253.59..1539
Establsh
18:46:01 (UTC)
13:46:01 (LCL) Idle time . . . . .: 00:01:55

CICS information
CICS
CICS
CICS
CICS
CICS

address space :
tran code. . .:
connection dir:
IPCONN name. .:
service name .:

CICSTS32
CWXN
In
N/A
HTTP

CICS
CICS
CICS
CICS
CICS

APPLID . . . .:
protocol . . .:
local port . .:
partner APPLID:
service desc .:

11
2,725
0
65,535
N/A
0
30.00
No

TCP segments out. .:

TCP bytes out . . .:
Receive data queued:
Current recv window:
Max segment size. .:
Duplicate ACKs . .:
TCP RTT variance .:
KEEPALIVE set . . .:

CICS1A
HTTP
5081
N/A
ABC HTTP

TCP flow information

TCP segments in . .:
TCP bytes in . . .:
Send data queued. .:
Current send window:
Congestion window .:
Total retransmits .:
TCP RTT (msec) . .:
TCP NODELAY set . .:

Page 54

10
2,488
0
130,150
536
0
478.00
No

2011 SHARE and IBM Corporation

For more information

URL

Content

http://www.twitter.com/IBM_Commserver

IBM Communications Server Twitter Feed

http://www.facebook.com/IBMCommserver

IBM Communications Server Facebook Fan Page

http://www.ibm.com/systems/z/

IBM System z in general

http://www.ibm.com/systems/z/hardware/networking/

IBM Mainframe System z networking

http://www.ibm.com/software/network/commserver/

IBM Software Communications Server products

http://www.ibm.com/software/network/commserver/zos/

IBM z/OS Communications Server

http://www.ibm.com/software/network/commserver/z_lin/

IBM Communications Server for Linux on System z

http://www.ibm.com/software/network/ccl/

IBM Communication Controller for Linux on System z

http://www.ibm.com/software/network/commserver/library/

IBM Communications Server library

http://www.redbooks.ibm.com

ITSO Redbooks

http://www.ibm.com/software/network/commserver/zos/support/

IBM z/OS Communications Server technical Support

including TechNotes from service

http://www.ibm.com/support/techdocs/atsmastr.nsf/Web/TechDocs

Technical support documentation from Washington

Systems Center (techdocs, flashes, presentations,
white papers, etc.)

http://www.rfc-editor.org/rfcsearch.html

Request For Comments (RFC)

http://www.ibm.com/systems/z/os/zos/bkserv/

IBM z/OS Internet library PDF files of all z/OS

manuals including Communications Server

For pleasant reading .

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