The read-only storage override option

CICS® obtains storage for the read-only DSAs (RDSA and ERDSA) from MVS read-only storage. You can override the selection of read-only storage for the RDSA and ERDSA by specifying NOPROTECT on the RENTPGM system initialization parameter.

The CICS loader automatically loads eligible modules into the RDSA and ERDSA; that is, if they are link-edited with the RENT attribute, and for the ERDSA with RMODE(ANY). You can specify RENTPGM=NOPROTECT if you do not want such modules to be loaded into read-only storage, perhaps because you are using a development aid package that sets break points in your application programs. When you specify RENTPGM=NOPROTECT, CICS still allocates separate read-only DSAs, but obtains CICS-key storage for the RDSA and ERDSA instead of read-only storage.

The RENTPGM=NOPROTECT override is only appropriate for development regions. In production CICS regions, RENTPGM=PROTECT provides the right level of protection for modules in the RDSA and ERDSA.