Determine the starting point for the BCDS scan

The starting point for the scan of the BCDS depends on:

Whether STARTKEY is specified in the command
Whether RESUME is specified in the command
Whether the key of the last data set processed (last-processed key) was saved at the end of the last EXPIREBV processing in this host

If STARTKEY is specified in the command, DFSMShsm starts with the BCDS record that the command specifies.

If RESUME is specified in the command and the saved last-processed key is not blank, DFSMShsm starts with the saved last-processed key.

If neither STARTKEY nor RESUME is specified in the command or if RESUME is specified but the saved last-processed key is blank, DFSMShsm starts with the first record in the BCDS.