Hi Bill,
I also have an Exec which calls my Writenr clist.. My point was counter
the idea that with Rexx, CLISTs are never necessary.
Regards,
David
On 2025-01-09 19:18, Bill Hitefield wrote:
I wrote a dinky CLIST to issue WRITENR. I call it from REXX as needed.
Bill Hitefield
-----Original Message-----
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On
Behalf Of David Spiegel
Sent: Thursday, January 9, 2025 5:42 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: ISREDIT CAPS ON OFF
Hi Tony,
CLISTs also have the WRITENR statement, which Rexx lacks.
Regards,.
David
On 2025-01-09 16:49, Tony Harminc wrote:
On Wed, 8 Jan 2025 at 19:51, Lennie Bradshaw
<lennie-brads...@outlook.com>
wrote:
CLIST design is over 50 years old I think.
CLISTs as we know them arrived with OS VS/2 Release 3, so the second
release of MVS around 1974 or so. Before that, on e.g MVT, SVS, and
the first MVS, CLISTs had no control flow statements - they were just
lists of commands with some substitution for arguments.
At introduction, everyone was all excited at the shiny new CLISTs, and
I remember well wondering why there was no lower case support, and if
it could be easily fixed. Indeed it could, and I found and happily
zapped out the upcasing and tried a CLIST with some lower case text in
it. It blew up all over the place, and I discovered that pretty much
all byte values beyond the upper case letters, numbers, and a few more
(i.e. roughly the JCL character set at the time) was being used as
internal syntactic markers for various aspects of the language. So much for
that quick fix.
No, I don't remember the details, but I imagine much of today's CLIST
processor is unchanged from the 1970s version, and the source code for
that is available if anyone wants to research it further.
But seriously, why does anyone use CLISTs today? There is to my
knowledge just one reason: there is tight integration with TSO parsing
and the CLIST header, whereas REXX requires that the command be
treated as a single string, and then parsed with the (unarguably powerful)
REXX parsing scheme.
But that doesn't allow for a syntax error to be discovered in the REXX
and the user prompted using TSO facilities; the REXX has to do all the
work itself.
Tony H.
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