VSAM index trap

VSAM has an index trap that checks each index record before writing it. The index trap is on by default.

VARY SMS,MONDS(IGWVSAM.BASE.INDEX.TRAP),OFF

VARY SMS,MONDS(IGWVSAM.BASE.INDEX.TRAP),ON

DISPLAY SMS,MONDS(IGWVSAM.BASE.VSAM.DEBUG.FEATURES) 

The trap catches the more common index breakages, but not all breakages:

1. High-used greater than high-allocated
2. Invalid index pointer
3. Duplicate index pointer
4. Out-of-sequence index record
5. Invalid section entry
6. Invalid key length
7. Horizontal pointer loop
8. Duplicate key
9. Incorrect segment count

The trap prevents a broken index, but the documentation generated might not be sufficient to determine the source of the problem. If the trap hits:

1. A console message is issued:

   IDAI1001E ERROR FOUND IN INDEX
   DSN:  SAMPLE.DATASET.INDEX
   REASON:  HIGH-USED GREATER THAN HIGH-ALLOCATED

   A similar message, IDAI1002E, is issued if an error is found in a catalog data set index.
2. A dump is generated.
3. The current request fails with logical-error RPL feedback 'xx08006D'.
4. No ABEND occurs.

If the data set is being shared properly, the systems programmer should:

1. Open a PMR and submit the following items:
   1. The dump
   2. An EXAMINE ITEST NODTEST, EXAMINE DTEST NOITEST, and LISTCAT of the data set taken after the trap hits
   3. DSS Prints of the index component after the trap hits
2. Rename and save the corrupted data set, in case IBM® Service needs additional documentation