In coding exit routines for DFSMShsm, you might sometimes find it useful to refer to a portion of a DFSMShsm data area. For descriptions and formats of general use DFSMShsm data areas, see z/OS DFSMShsm Diagnosis. That book provides descriptions of fields in the data areas, the meaning and use of those fields, and the offsets and the byte and bit patterns for the fields. Data area cross-reference information follows the description of each record.

DFSMShsm uses subpools, which it shares within its subtasks, through the SHSPL parameter of the ATTACH macro. The subpools are 1, 6, 7, 10, 11, 12, 13, and 78. When you write exit routines or modify DFSMShsm and that code requires GETMAIN processing from one of these subpools, the FREEMAIN request must ask for the amount of storage requested by the GETMAIN and not a complete subpool FREEMAIN.