Processing GSAM databases

GSAM databases are available to application programs that can run online in IMS batch message processing (BMP) regions (message-driven or non-message-driven) or Java™ batch processing (JBP) regions or standalone in DLIBATCH 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 database, the program treats it like a sequential file. The physical z/OS® access methods that GSAM databases support are BSAM on direct access and tape devices and VSAM on direct-access storage devices (DASD). VSAM data sets must be non-keyed and non-indexed entry-sequenced (ESDS). GSAM does not support temporary, SYSIN, or SYSOUT 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.