During LOCATE, SCRATCH, RENAME, and OPEN processing, certain conditions can be encountered that require intervention by DFSMShsm. Any data set function that may require DFSMShsm participation results in a system request being sent to DFSMShsm. Of course, DFSMShsm user commands entered from TSO are sent to DFSMShsm for processing. If DFSMShsm has been active during the current IPL of the system but is not currently active when the preceding conditions occur, message ARC0050A, ARC0052A, or ARC0055A can be issued to indicate that DFSMShsm must be started to process the system request or user command.

When DFSMShsm is inactive, the messages just listed are always issued if the system request detects that a data set is cataloged on volume serial MIGRAT or if a DFSMShsm user command is submitted from TSO. If the system request results in a DSCB-not-found condition, the messages discussed earlier are issued only if DFSMShsm is not in debug mode at the time of DFSMShsm shutdown.