Specifying user IDs for MSC security

If you use RACF®, exit routines, or both to perform MSC security checking, use the second positional parameter of the MSCSEC= startup parameter in the DFSDCxxx PROCLIB member to specify the user ID on which to base security checking.

The parameter options are:

CTL: Specifies that RACF and exit routines use the user ID of the receiving IMS control region. This is the default.
MSN: Specifies that RACF and exit routines use the MSNAME as the user ID.
USR: Specifies that RACF and exit routines use the user ID of the inputting terminal.

Note: User IDs that are defined in RACF resource classes must be unique. When you define user IDs for MSC security, watch for conflicts with existing user IDs.