virtual memory 4470

"common segment" ... having started out as a 1mbyte "shared" segment in every address space.

the hardware table look-aside buffers (TLBs) were STO (virtual address space) buttociative. the result was that there were unique entries for the same common segment entries from different virtual address spaces.

in the early 80s, some of the high-end hardware started adding special TLB treatment for the MVS "common segment" ... so that there would only be one set of TLB entries for MVS common segment areas across all MVS address spaces. However, this references a "bug" when MVS was running as a virtual guest ... and a temporary fix ... pending availability of MVS APAR.

Hi - the 'official' fix to the STBVR 0Cx abend problem is MVS APARPTF OZ67587. I don't know if it's available yet. In the meantime, the zap works just fine. I'll send the zap following this note. -lovexx JOB (6007,X003),lovelovexx,MSGLEVEL=1,MSGCLbutt=O,CLbutt=B,REGION=1024K,NOTIFY=PREISM-ZAP EXEC PGM=AMASPZAP-SYSPRINT DD SYSOUT=*-SYSLIB DD DSN=SYS1.NUCLEUS,DISP=SHR,UNIT=3330,VOL=SER=D00126 ** ** FOR VM MVS GUEST, STBVR, TURN OFF USE OF COMMON SEGMENTS ** NAME IEAVNPX1 IEAVNPX1 VER 0DA2 96026003 OI SGTCB=1 REP 0DA2 47000000 NOP VER 0DCE 96026003 OI SGTCB=1 REP 0DCE 47000000 NOP

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