On Tue, 22 May 2018 15:27:32 -0400, Thomas David Rivers wrote:
>The BPX loadhfs function (BPX1LOD) loads an HFS executable
>into memory.
>
>It seems, that sometimes, this is loaded into writable memory
>and sometimes into read-only memory.
>
>There doesn't seem to be a way to indicate which is desired.. is there
>some OS-interface that writable memory be used?
>
What was Peter H. (informally?) quoting without citation?
In: z/OS IBM MVS Program Management: User's Guide and Reference
Version 2 Release 3 SA23-1393-30
Chapter 6. Binder options reference
Binder options
REUS: Reusability options`
RENT
The module is reenterable. It can be executed by more than one
task at a time. A task can begin executing it before a previous
task has completed execution. A reenterable module is ordinarily
expected not to modify its own code. In some cases, MVS protects
the reentrant module's virtual storage so that it cannot be
modified except by a program running in key 0. These cases
include programs which the system treats as having been loaded
from an authorized library, and also programs running under UNIX
unless a debugging environment has been specified.
Reenterable modules are also serially reusable.
So, WAD.
I dislike some things about this:
o "include" is undesirably vague. The Ref. should specify exactly
the cases in which ... programs are [so] treated. A precise "are"
is preferable to the imprecise "include". What other cases may
there be? "[T]reats as having been ..." is likewise vague. Provide
at least a citation of an explanation of what this means.
o Simpler Is Better. I see no good reason to treat "programs running
under UNIX" differently from other programs.
o "ordinarily expected". Is this a retreat from the earlier well-known
rule (cited by Peter) that a RENT program was allowed to modify its
own code given proper serialization?
-- gil
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