Configuring CICS for TCP/IP
CICS TCP/IP Platform Requirements
TCP/IP version 3R2
CICS version 3.3 or later
Connections to CICS using TCP/IP
CICS uses the IBM-supplied Concurrent Listener (program EZACIC02, transaction ID CSKL) to establish an interaction with TCP/IP. The Listener is a transaction that automatically starts when CICS TCP/IP is started and enabled. When the Listener starts, it obtains a socket on which it can "listen" for connection requests from TCP/IP. The Listener binds the socket to a specified port, and then waits for a client request on that port. TCP/IP maintains a relationship of a port number to a CICS job. When a client makes a request on a port associated with CICS, TCP/IP forwards the connection request to the Listener in that CICS job.
For additional details about the CICS MS LINK communication model, see CICS MS LINK (TCP/IP).
TCP/IP-to-CICS Configuration
A TCP/IP port number is associated with a CICS region in the TCP/IP profile data set (hlq.PROFILE.TCPIP). The port statement is used to define this relationship. For example, the following is a port statement that associates port 3000 with CICS region CICSRG:
3000 TCP CICSRG
CICS-to-TCP/IP Configuration
The following sample host definition shows configuration parameters for CICS-to-TCP using the EZAC transaction:
EZAC,DEFINE
ENTER ONE OF THE FOLLOWING
CICS ===> yes Enter Yes|No
LISTENER ===> Enter Yes|No
EZAC,DEFINE,CICS
ENTER ALL FIELDS
APPLID ===> CICSRG APPLID of CICS System
EZAC,DEFINE,CICS
OVERTYPE TO ENTER
APPLID ===> CICSRG APPLID of CICS System
TCPADDR ===> TCPIP Name of TCP Address Space
NTASKS ===> 020 Number of Reusable Tasks
DPRTY ===> 000 DPRTY value for ATTACH
CACHMIN ===> 015 Minimum Refresh Time for Cache
CACHMAX ===> 030 Maximum Refresh Time for Cache
CACHRES ===> 010 Maximum number of Resolvers
ERRORTD ===> CSMT TD Queue for Error Messages
The following sample host definition shows configuration parameters for the CICS Concurrent Listener using the EZAC transaction:
EZAC,DEFINE
ENTER ONE OF THE FOLLOWING
CICS ===> Enter Yes|No
LISTENER ===> yes Enter Yes|No
EZAC,DEFINE,LISTENER
ENTER ALL FIELDS
APPLID ===> CICSRG APPLID of CICS System
NAME ===> CSKL TRANSACTION NAME OF LISTENER
EZAC,DEFINE,LISTENER
OVERTYPE TO ENTER
APPLID ===> CICSRG APPLID of CICS System
TRANID ===> CSKL Transaction Name of Listener
PORT ===> 03000 Port Number of Listener
IMMEDIATE ===> YES Immediate Startup Yes|No
BACKLOG ===> 010 Backlog Value for Listener
NUMSOCK ===> 050 Number of Sockets in Listener
MINMSGL ===> 004 Minimum Message Length
ACCTIME ===> 060 Timeout Value for ACCEPT
GIVTIME ===> 030 Timeout Value for GIVESOCKET
REATIME ===> 000 Timeout Value for READ
FASTRD ===> YES Read Immediately Yes|No
TRANTRN ===> YES Translate TRNID Yes|No
TRANUSR ===> YES Translate User Data Yes|No
SECEXIT ===> Name of Security Exit
Before you attempt to use the TCP/IP connection, do the following:
Verify that you have a TCP address space running on the host. (You should be able to PING the host at its IP address or DNS name.) Record the IP address; you will need to know it later when you use Transaction Integrator (TI) Manager to define a TCP/IP remote environment for the CICS region.
Check that the CICS region supports TCP/IP, and that the IBM-supplied Listener (program EZACIC02, transaction ID CSKL) is defined. These procedures are described in chapter 5 of TCP/IP V3R2 for MVS: CICS TCP/IP Socket Interface Guide (IBM Document #SC31-7131). Note that this is a CICS TS version 1.2 document, but the configuration is also supported in CICS version 4.1.
Determine the IP port number of the Listener (EZAC DISPLAY LISTENER); you will need to know it when you use TI Manager to define a TCP/IP remote environment for the CICS region.
Start the IBM-supplied Listener (EZAO START) and check the CICS view of the Listener status (execute the CEMT INQUIRE TASK command, and verify that CSKL is running).