Your suspicions were quite correct. After some futzing around the opening
logic finally does:
if ((pcapfd = fopen("DD:PCAPFN", "ab+,lrecl=1")) == NULL) {
which looks like it must takes precedence over the OTRUNC.
Many thanks for pointing me in the right direction.
Best wishes / Mejores deseos / Meilleurs vœux
Ian ...
On Friday, December 9, 2022 at 05:37:54 PM GMT+1, Paul Gilmartin
<[email protected]> wrote:
On Fri, 9 Dec 2022 08:54:03 +0000, Ian Worthington wrote:
>When I run JCL with
>//PCAPFN DD PATHOPTS=(OCREAT,ORDWR,OTRUNC),
>// PATHMODE=..., PATH=... // FILEDATA='BINARY'
>
>any existing file gets extended. Yet
>
What program did you name on the EXEC PGM= statement?
It's possible that the program overrides PATHOPTS. (It shouldn't
matter if step initiation performs an open() with the coded PATHOPTS.)
How do other programs behave?:
o IEBGENER SYSUT2?
o IEFBR14? (Is the truncation performed at open() or at the first write()?)
>https://www.ibm.com/docs/en/zos/2.4.0?topic=definition-status-group
> clearly states that:
>
> - OTRUNC
> - Specifies that the system is to truncate the file length tozero if all
>the following are true:
> - The file specified on the PATH parameter exists.
> - The file is a regular file.
> - The file successfully opened with ORDWR or OWRONLY.
--
gil
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