[comp.lang.asm370] CESD Data in Load Modules

F66204@BARILVM.BITNET (Shaul Wallach) (03/19/91)

I'm having a small problem understanding the CESD data the linkage
editor generates for a load module, in particular, bit 1 of the
flag byte (byte 13, starting from 1) in the 16 byte field. In my
version of MVS/370 Link Editor Logic this byte is described as
xxxxRRAA, where xxxx is "not used", and RRAA contain the RSECT,
RMODE and AMODE bits. The Assembler H V.2 Programming Guide
likewise documents only the RMODE and AMODE bits. However, many
CESD entries of my modules (when linked by the MVS/XA linkage
editor) contain a "1" as the second "x" bit in this flag. Does
anybody know what it means?

Thanks,

Shaul Wallach

USERALVE@RPITSMTS.BITNET (Brian Eliot) (03/20/91)

Versions of Assembler H prior to Version 2, and presumably other
language translators as well which predated the definition of
the RSECT, AMODE, and RMODE control section attributes, generated
the ESD attribute byte as a blank (X'40').  My guess is that the
CESD bit 1 being on is an artifact of these older object modules.
Assembler H Version 2 now generates bit 1 as a zero, and presumably
for compatibility with old object modules bit 1 has no meaning.

Brian Eliot
Information Technology Services
Rensselaer Polytechnic Institute