Where does the COMMAREA reside in CICS?

Question

On this page from IBM, I read the following -

"The client application communicates with the CICS server program by using a data area called a COMMAREA, which is passed to the CICS region on the call."

My question is, where is this data area located?

Answer 1

CICS will maintain it for you between instances. For you to know would totally allow you to break that abstraction.

In some cases it will remain in CICS storage. If you are in a multi region setup, it will very likely be passed about using any of a variety of options, VSAM datasets, shared memory, VTAM or TCP/IP.

But you really don't want to know. The first time your transaction runs, it can set up whatever commarea it likes. On every RETURN, except the last one, pass that commarea back to CICS. CICS will then hand you back your commarea totally undisturbed the next time your transaction runs.

Also, commareas have some serious limitations. If you are doing new development, you should be thinking channels and containers, the remove the commarea limitations.