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CICS Resident Programs

The installation process defines the following CA IPC programs to CICS as RES=YES:

These nine programs must always be CICS RES=YES. If they are not RES=YES, the result could be CICS abends or storage violations.

Because resident programs are treated as part of the CICS nucleus, which is loaded at start-up, you can improve performance by reducing the number of I/O events needed to load frequently accessed non-resident programs. Increasing the number of resident programs reduces the amount of Dynamic Storage Area (DSA) available for transaction processing. Performance and CICS storage requirements must both be considered to determine any benefits from increasing the number of resident programs.

You can modify the resident option for any program definition using RDO in CICS.