For communication between CICS® regions that are in different MVS™ images, you can use a SNA access method, such as ACF/VTAM, to provide the necessary communication protocols. This form of communication between regions through SNA is called intersystem communication (ISC). (You can also use ISC in the same CPC, through the application-to-application facilities of ACF/VTAM.)
This topic outlines how to include ISC in a CICS region.
For information about the design and implementation of intersystem communication facilities, see the CICS Intercommunication Guide .
Unlike MRO, there are no special MVS operating system requirements for CICS intersystem communication.
You must include the following management programs in your CICS regions, (by specifying the system initialization parameters that are given in parentheses):
Intersystem communication requires VTAM® support, and you must specify VTAM=YES as a system initialization parameter. If VTAM is running during CICS initialization, CICS opens the VTAM ACB. If VTAM is started after CICS, opening the VTAM ACB fails, and you must open it using the CEMT SET VTAM OPEN command when VTAM is available. CICS regions cannot communicate until they have established the VTAM connection.
Before you can use ISC, you must define and install connections with attributes appropriate to your CICS (and VTAM) environment. If you intend using APPC for your ISC communications, you can take advantage of the autoinstall for APPC connections function. For information about defining connections, and about using the autoinstall for APPC connections function, see the CICS Resource Definition Guide.
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