> I am correct in assuming that the dataspace must be created by a > running STC or JOB, and when shutsdown the dataspace Is deleted ?
That is correct. A SCOPE=COMMON data space cannot persist beyond the termination of its creator. On the other hand, 64-bit common storage is never implicitly freed by the system, and thus can persist beyond the termination of its creator. Also, starting with z/OS 1.12, z/OS turns on the common segment bit in the Segment Table Entry for 64-bit common segments. This cannot be done for SCOPE=COMMON data spaces. So 64-bit common storage may incur fewer TLB misses, and use fewer TLB entries, compared to a SCOPE=COMMON data space. Also, segment and page tables for data spaces are virtualized in RSM data spaces (SYSDSxxx data spaces owned by the RASP address space). So additional real storage is required for segment and page tables of these RSM data spaces. And, there may be TLB misses while accessing the page and segment tables of the data spaces, and TLB misses while accessing the page and segment tables of the SYSDSxxx data spaces. Region, segment, and page tables for 64-bit storage are not virtualized anywhere - z/OS accesses them via real addresses. 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
