Bruce
> None (of) the documentation explicitly defines which storage is related to
FIXED.
The following is a list of the sources of information on the Communications
Storage Manager (CSM) and particularly the IVTPRM00 member:
- MVS Initialization and Tuning Reference
Chapter 63. IVTPRM00 (Communication Storage Manager)
- z/OS Communications Server SNA Network Implementation Guide
Chapter 14. Application programs
Communications storage manager (CSM)
Appendix C. Communications storage manager
- z/OS Communications Server New Function Summary
Chapter 1. Planning to use new functions
Defining SNA data sets
Parmlib member for Communication Storage Manager (CSM)
- z/OS Communications Server CSM Guide
mainly for the CSM API
Additional information is integrated into SNA Operation, SNA Messages, SNA
Diagnosis Vol 1, Techniques and Procedures and even SNA Customization.
Probably for information on how to set up, monitor and *alter* CSM storage
for the purposes of optimizing performance you need Appendix C of the SNA
Network Implementation Guide - 3 1/2 pages. The section in the New Function
Summary manual is the most extensive description of IVTPRM00 (2 pages). In
comparison what is said in the MVS Initialization and Tuning Reference chapter
is pretty useless. I believe the chapter is there for form's sake only!
You can probably see that the CSM is a semi-independent component of
VTAM supplied in order to support improved performance for moving chunks of
data within the Central Electronic Complex (CEC). It has particular uses for
some CS SNA and IP functions but - having an external API - I guess anyone
might care to use it. IVTPRM00 seems to provide parameters to guide the CSM.
It's interesting that there is a statement in the CSM Guide which says using
applications should provide guidance over how to set the parameters. I expect
that Appendix C is that guidance from the CS SNA and IP components.
>From the end of section "Application responsibilities for using CSM" in
>Chapter
1:
<quote>
The applications use of CSM should be documented so that the installation
can adjust ECSA and fixed storage limits in the CSM parmlib member as
necessary. This information should be available in application installation
documentation so that necessary changes to the limits can be made prior to
application installation.
</quote>
Incidentally, your precise question may be answered by the following sentence
from the New Function Summary section:
<quote>
Note that the fixed maximum represents the total fixed storage above and
below the 2-gigabyte bar.
</quote>
Also the so-called "IBM Health Checker for z/OS" can have opinions over your
IVTPRM00 choices. Just have the salt cellar handy!
Although I often have a shot at any VTAM-related questions which arise, CSM
is a bit obscure and I can't tell you any more than can be found in the fine
manuals.
One little insight which may or may or may not be useful is that the way the
CSM handles its buffer pools has the "look and feel" of the way - which I used
to teach - that VTAM has always handled its traditional buffer pools - so no
surprises there then!
Chris Mason
On Tue, 10 Nov 2009 06:29:29 -0600, Bruce Hewson
<[email protected]> wrote:
>Hi folks,
>
>I am trying to get to the bottom of the Communications Storage Manager
>(CSM - z/OS 1.9) parameter FIXED. I understand the ECSA parameter,
>because I know where and how big our ECSA is.
>
>But what I don't have a clear understanding about, is the FIXED parameter.
>
>1. Is the FIXED parameter referring to how many ECSA pages are FIXED
>
>2. CSM uses 2 dataspaces, 1 for 31 bit storage, 1 for 64 bit storage. Is the
>FIXED parameter somehow related to this dataspace storage?
>
>3. Or is FIXED used for some other purpose?
>
>None the documentation explicitly defines which storage is related to FIXED.
>
>Hope someone can help me.
>
>Thanks
>Bruce Hewson
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