Oppolzer - Informatik / Blog

Am 20.03.2015 um 01:07 schrieb W.F.:
> On Thu, 19 Mar 2015 18:43:45 -0500, D.S. wrote:
>
>> If you are not adverse to chasing MVS control blocks from COBOL code,
>> (instead of using a system interface like RDJFCB), then take a look at some
>> sample COBOL code written by Gilbert Saint-Flour at the bottom of this page:
>> http://gsf-soft.com/Freeware/
>>
>> In particular, COB2JOB and COB2SYS.
>>
> I don't think you can safely get dsnames for allocated ddnames just by chasing
> control blocks. That _can_ work with if the system is configured to have SWA
> below the line, but I wouldn't want to count on having that configuration in
> effect. As soon as you have SWA above the line I think you have to use SWAREQ or
> some other system service to do at least part of the processing.
>

That's what I did: all the control block chasing in C, and SWAREQ with a small
ASSEMBLER subprogram, callable from C.

This is a general pattern for enabling C programs to do system related
processing: identify services that can't be done using pure C and write small
ASSEMBLER function blocks for them which can be called by C. I have written lots
of them over the years, one for example: get the current contents of the general
registers (escpecially register 13); that enables me to do a stack trace
(calling hierarchy, including function names etc.) without using ASSEMBLER ...
all in C.

Kind regards

Bernd

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