An area of storage allocated above the 16MB line and used for eligible, reentrant CICS and user application programs, which must be link-edited with the RENT and RMODE(ANY) attributes. The storage is obtained in key 0, non-fetch-protected storage, if the system initialization parameters include RENTPGM=PROTECT. If RENTPGM=NOPROTECT is specified, the ERDSA is in CICS-key storage.