On Fri, Feb 05, 2021 at 03:53:17PM -0500, Joseph Reichman wrote:
> I opened a dcb load library with the same load mod name as the first
> Did an attach DCB= TASKLIB=
>
> Didn’t pick it up from there as the module from the first load lib
> with same name was linked REUS
It helps to know where to look things up:
** module reusability
z/OS Version 2 Release 3
MVS Program Management: User's Guide and Reference
SA23-1393-30
ieab100_v2r3.pdf
see pdf page 48, page 28
nonreusable:
single use only, need a new copy if used (or in use)
serially reusable:
only a single use at a time, later requestors need to wait for use
to complete {ATTACH/LINK/XCTL/SVC 3-exit keep track of module
in use status, note that when using LOAD/CALL/DELETE the system
doesn't t known when you call or return from the module}
{In the case of the system keeping track of the module use, it
may delay start of an execution until the current use is complete}
reenterable (reentrant):
concurent execution by multiple tasks. If modifies it's own
data areas it must do it's own serialization.
refreshable:
all or part of the module can be replaced at any time without notice
by the operating system. *therefore* must not modify itself in
any way.
{** beware **
some module attributes and authority levels force modules to
beloaded into different key storage and/or protected storage.
This may affect fetch access too}
Linkage editor processing of attributes:
refer rent reus are all treated as separate attributes
Binder
only a single attribute and implies/overrides lower attributes
refer > rent > reus > none {guess, doesn't explicitly say}
** module search order
z/OS Version 2 Release 3
MVS Programming: Assembler Services Guide
SA23-1368-30
ieaa600_v2r3.pdf
see pdf page 69, page 43
The search for a load module:
- requesting tasks' load list
- job pack area
- requesting task's task library (and up parent tree of tasklibs)
- steplib
- link pack area
- link library
{I think of joblib/steplib as a tasklib set by the attacher of the
job step task...}
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