Activating intersystem communication over z/OS Communications Server

To provide the necessary protocols to support communication between CICS® regions that are in different z/OS® images, or in different z/OS sysplexes, ISC over SNA uses the ACF/Communications Server access method.

You can also use ISC over SNA in the same CPC, through the application-to-application facilities of ACF/Communications Server.

You must include the following management programs in your CICS regions, by specifying the system initialization parameters that are given in parentheses:

DFHISC – the intersystem communication program (ISC=YES).
DFHTCP – the terminal control program (TCP=YES is the default).

Establishing ISC over SNA

Intersystem communication over SNA requires z/OS Communications Server support. CICS regions cannot communicate until they have established the z/OS Communications Server connection.

Specify VTAM=YES as a system initialization parameter.

If the z/OS Communications Server is running during CICS initialization, CICS opens the z/OS Communications Server ACB.

If the z/OS Communications Server is started after CICS, opening the z/OS Communications Server ACB fails, and you must open it using the z/OS Communications Server CEMT SET VTAM® OPEN command when the z/OS Communications Server is available.