The SIGNON command enables your application program to associate a new user ID with the current terminal, and SIGNOFF signs off a user ID from a terminal. However, in earlier releases there are some potential inconsistencies in the way the SIGNON and SIGNOFF requests are handled. In CICS® TS 1.3 and earlier, CICS recognizes the sign-on immediately, and establishes the specified user's security and operating attributes for the terminal. The transaction (and any associated task-related user exits, function shipping, or distributed transaction processing) may have invoked other resource managers (for example, IMS™, DB2®, or VSAM). It is unpredictable whether these other RMs recognize the sign-on before the transaction terminates, and thus you can only be sure that the new user attributes apply for all resource managers invoked by subsequent transactions at the terminal. The unpredicatability applies equally to SIGNOFF. To remove this inconsistency, CICS now processes a SIGNON and SIGNOFF command in way that does not affect the current transaction issuing the command.
When you use the SIGNON and SIGNOFF command, the following rules now apply:
Review the use of SIGNON and SIGNOFF in your application programs, and check to see if they might be affected by the change. If your application programs are using SIGNOFF and SIGNON in a transaction that performs no other significant work (for example, does not access or update recoverable resources, or does not communicate with partner systems) they are unaffected by the changed behavior.
If you have applications that cannot tolerate the change in the SIGNON and SIGNOFF process, CICS provides a new global user exit point (XSNEX) and sample global user exit program that will enable CICS to handle EXEC CICS SIGNON and SIGNOFF as in earlier releases. Note that XSNEX is a migration aid only, and you should consider removing all application dependency on the old behavior.
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