> Details, please?

  In z/OS 2.5 TSO/E REXX Reference, SA32-0972-50, SUBCOM, P. 230, the text

     "You can use the SUBCOM command in REXX execs that run in any address 
space, TSO/E or non-TSO/E.
     That is, SUBCOM is available from the TSO and MVS host command 
environments."

  Is unclear. Depending on the interpretation of the first senetnce, the second 
sentence is incorrect, although removing "that is" would make it correct.

  More concretely, it is unclear which of these is valid:

     ADDRESS ATTACH    foo
     ADDRESS ATTACHMVS foo
     ADDRESS ATTACHPGM foo
     ADDRESS CONSOLE   foo
     ADDRESS CPICOMM   foo
     ADDRESS ISPEXEC   foo
     ADDRESS ISREDIT   foo
     ADDRESS LINK      foo
     ADDRESS LINKMVS   foo
     ADDRESS LINKPGM   foo
     ADDRESS LU62      foo
     ADDRESS MVS       foo
     ADDRESS SH        foo
     ADDRESS SYSCALL   foo

>  I'm uneasy that ADDRESS TSO SUBCOM et al. contravene the
> specification of ADDRESS in the Rexx Ref.:

Not at all. Assu7ming that IEFBR14 either has the value IEFBR14 or is 
uninitialized,  ADDRRESS LINKMVS IEFBR14 interpretsd the string "IEFBR14" in 
the host environment LINKMVS. In that environment, REXX parses the value into a 
program name and a parameter, then does a LINK to that program with the parsed 
parameter. The LINK and LINKPGM environments do the same, except for the 
details of parsing the value and construction the plist.

ADDRESS SH follows the same pattern: parse the value and do something with it. 
In this case, the something is to invoke the shell with the specified parameter.

The mechanism is quite general, and IMHO is well designed; certainly more so 
than, e.g., SIGNAL.


--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3

________________________________________
From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of 
Paul Gilmartin [0000000433f07816-dmarc-requ...@listserv.ua.edu]
Sent: Sunday, May 8, 2022 2:02 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: What is SUBCOM?

On Sun, 8 May 2022 15:33:46 +0000, Seymour J Metz  \ wrote:

>I've submitted an RCF.
>
Details, please?

I'm uneasy that ADDRESS TSO SUBCOM et al. contravene the
specification of ADDRESS in the Rexx Ref.:
    ADDRESS temporarily or permanently changes the
    destination of commands. Commands are strings
    sent to an external environment.  ...

That's only mostly true.  In contrast,
    ADDRRESS LINKMVS IEFBR14
        expands as macro LINK EP=IEFBR14
    ADDRESS SH  ':'
        expands as "sh  -c ':'"
etc.
It's a misdesign; chaotic, that Rexx induces a restriction on
the name space of an "external environment", particularly
given that ADDRESS MVS, which is peculiar to Rexx, not
an external environment, exists and serves the need.

Also, the section "Reserved command names" should appear
not only in the Rexx Ref., but also, or even stead, in "z⧸OS
TSO⧸E Programming Guide" since it is a caution to authors
of TSO/E Command Processors, not Rexx execs.

(Yes, I'm also uneasy that lately initiators treat PGM=IEFBR14
as an exception.  It should have been done by introducing a
new keyword.)

--
gil

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