🚀 go-pugleaf

blmblm@myrealbox.com <blmblm@myrealbox.com> writes:
> Was there an acronym/initialism for this COMMON area?  My memory of
> doing junior-level systems work on MVS systems is telling me that 
> there was one, but not what.   ?

"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) associative. 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.

Date: 18 February 1983, 12:30:13 EST
From: xxxx
 
Hi - the 'official' fix to the STBVR 0Cx abend problem is MVS APAR/
PTF 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.
 
//xxxxx JOB (6007,X003),xxxxxxxx,MSGLEVEL=1,MSGCLASS=O,CLASS=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
//

-- 
Anne & Lynn Wheeler | http://www.garlic.com/~lynn/