To access information from a native VSAM data set, CA IDMS/DB converts DML statements issued by the application program into record-level (not control-interval) VSAM macro variations (for example, ACB, RPL) and passes control to VSAM. No changes have to be made to the VSAM data set. A local run unit or central version appears to VSAM as a single application that opens VSAM data clusters, activates VSAM paths using local-shared resources (LSR) or nonshared resources (NSR), accesses data records, and closes the clusters and paths.
The following table lists different VSAM structures and the CA IDMS/DB DML functions that can be used to access the VSAM structures.
DML Functions for Native VSAM Data Set Access
|
CA IDMS/DB DML Statement |
VSAM Structure |
|---|---|
|
STORE last within area |
ESDS |
|
STORE direct by db-key |
RRDS |
|
STORE physical sequential |
KSDS |
|
ERASE |
KSDS or RRDS |
|
FIND/OBTAIN FIRST/NEXT WITHIN SET |
KSDS or ESDS with a primary index or alternate indexes |
|
FIND/OBTAIN LAST/PRIOR WITHIN SET |
KSDS or ESDS with a primary index or alternate indexes |
|
FIND/OBTAIN WITHIN SET USING SORT KEY |
KSDS or ESDS |
|
FIND/OBTAIN FIRST/NEXT WITHIN AREA |
KSDS, ESDS, or RRDS |
|
FIND/OBTAIN LAST/PRIOR WITHIN AREA |
KSDS, ESDS, or RRDS |
|
FIND/OBTAIN CALC |
KSDS or ESDS with a primary index or alternate indexes |
|
FIND/OBTAIN CALC DUPLICATE |
KSDS or ESDS with a primary index or alternate indexes |
|
FIND/OBTAIN DB-KEY |
ESDS or RRDS |
|
MODIFY, changing CALC key or sort key |
KSDS or ESDS with a primary index or alternate indexes |
|
MODIFY, without changing CALC key or sort key |
KSDS, ESDS, or RRDS |
|
MODIFY, changing record length |
KSDS |
|
ROLLBACK following STORE (without restore and rollforward) |
KSDS or RRDS |
|
ROLLBACK following ERASE (without restore and rollforward) |
KSDS or RRDS |
|
ROLLBACK following MODIFY (without restore and rollforward) |
KSDS or RRDS |
|
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