Processing GSAM databases

GSAM databases are available to application programs that can run as batch programs in batch message processing (BMP) regions, transaction-oriented BMPs, or Java™ batch processing (JBP) regions.

If your application program accesses GSAM databases, as you design your program consider that:

• An IMS™ program can retrieve records and add records to the end of the GSAM database, but the program cannot delete or replace records in the database.
• You use separate calls to access GSAM databases. (Additional checkpoint and restart considerations are involved in using GSAM.)
• Your program must use symbolic CHKP and XRST calls if it uses GSAM. Basic CHKP calls cannot checkpoint GSAM databases.
• When an IMS program uses a GSAM data set, the program treats a GSAM data set like a sequential non-hierarchic database. The z/OS® access methods that GSAM can use are BSAM on direct access, unit record, and tape devices; and VSAM on direct-access storage. VSAM data sets must be non-keyed, non-indexed, entry-sequenced data sets (ESDS) and must reside on DASD. VSAM does not support temporary, SYSIN, SYSOUT, and unit-record files.
• Because GSAM is a sequential non-hierarchic database, it has no segments, keys, or parentage.

Java application programs running in JBP regions can access GSAM databases by using the IMS Java dependent region resource adapter.