On Fri, 28 Apr 2023 19:37:39 +0000, Schmitt, Michael wrote:
>I know how to have a COBOL program on z/OS use a data set name that isn't
>determined until runtime, via an environment variable. My question is can you
>use one file (i.e. one select/assign and one FD) to write to different DD
>names, that were already allocated in the JCL?
>
When I wear my ill-fitting MVS hat, I find it bizarre that any HLL is
DDNAME-ignorant. It's what most of them require. Think EXECIO.
But COBOL ...
A DDNAME is a component of I/O abstraction, a handle for a data set,
analogous to the way in UNIX that a descriptor is a handle for a
pathname. And some UNIX utilities accept only pathnames, not
descriptors. But UNIX-like systems that I nave used, Solaris, Linux,
MacOS, OMVS, provide a pseudo-mountpoint, "/dev/fd/" to treat a
descriptor as a pathname. This is not required by POSIX.
For example:
exec 42</etc/services
wc /dev/fd/42
... just works.
A modest proposal: Wouldn't it be nice if z/OS provided a pseudo-HLQ
such as "DDHLQ.<ddname>" to meet the requirements of languages
such as COBOL which demand a DSN, not a DDNAME, so given
SYSUT42 a program could form "DSN=DDHLQ.SYSUT42", look it up
in the catalog, OPEN, and read it.
RFE, anyone?
--
gil
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