DSAs in 31-bit storage: ECDSA, EUDSA, ESDSA, ERDSA, and ETDSA

The group of CICS® dynamic storage areas above the line (above 16 MB but below 2 GB) are collectively called the extended dynamic storage area (EDSA). This storage is 31-bit storage. The CICS system initialization parameter EDSALIM specifies the limit on the total size of these dynamic storage areas. The EDSALIM value be smaller than the REGION size specified for the CICS job, or smaller than the limit specified in the IEFUSI exit.

The amount of storage specified by the EDSALIM value is allocated as guaranteed storage at system initialization. At initialization, CICS performs GETMAIN to get and reserve the EDSALIM storage, and if the GETMAIN fails, which means that the value is too large, CICS will allocate smaller default amounts instead.

Within this per-allocated storage, CICS manages the following dynamic storage areas automatically, and you do not need to specify their individual sizes:

ECDSA (Extended CICS DSA)

The storage area for all non-reentrant CICS-key RMODE(ANY) programs, all CICS-key task-lifetime storage in 31-bit storage, and CICS control blocks that reside in 31-bit storage. The ECDSA is always allocated from CICS-key storage.

EUDSA (Extended user DSA)

The storage area for all user-key task-lifetime storage in 31-bit storage (above the line). If you specify the system initialization parameter STGPROT=YES for the CICS region, which is the default, the EUDSA is allocated from user-key storage. If you specify STGPROT=NO, the EUDSA is allocated from CICS-key storage.

ESDSA (Extended shared DSA)

The storage area for any non-reentrant user-key RMODE(ANY) programs, and also for any storage obtained by programs issuing CICS GETMAIN commands for 31-bit storage with the SHARED option. If you specify the system initialization parameter STGPROT=YES for the CICS region, which is the default, the ESDSA is allocated from user-key storage. If you specify STGPROT=NO, the ESDSA is allocated from CICS-key storage.

ERDSA (Extended read-only DSA)

The storage area for all reentrant programs and tables in 31-bit storage. If you specify the system initialization parameter RENTPGM=PROTECT for the CICS region, which is the default, the ERDSA is allocated from read-only key-0 protected storage. If you specify RENTPGM=NOPROTECT, the ERDSA is allocated from CICS-key storage.

ETDSA (Extended trusted DSA)

The storage area for any security-related CICS control blocks that reside in 31-bit storage. The ETDSA is always allocated from CICS-key storage.