> Allocating 100 MB area, I found that the first page in the newly > allocated area always seems to be backed by real storage upon return > from STORAGE OBTAIN. Is this true? Where is this documented?
For requests where RSM is involved: If you specify BACK=ALL or BACK=NONE on the STORAGE macro, that is treated as a hint by RSM, and may be what gets done. If you specify or default to BACK=BYSPT, the backing depends on the subpool. For most non-fixed subpools, we back the first page (assuming there is sufficient real storage available). Except if you are running on a z13 machine with APAR OA46291 installed, in which case backing storage may not been freed during a subsequent FREEMAIN, so it remains backed for a subsequent GETMAIN. For requests where RSM is not involved (when the request is satisfied from free storage represented by a DFE or FQE), the backing is unchanged. Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
