Kevin
Active User
Joined: 25 Aug 2005
Posts: 256
|
|
|
|
This is a quote from another Forum that is quite nice:
| Quote: |
This is a common problem for new users; they don't understand the difference between Rexx and ISPF or TSO and ISPF. You absolutely need to understand those differences before you can use the services of ISPF within a Rexx exec or any other kind of program.
In a nutshell:
* Rexx is a scripting language available on many, many platforms. One of the places it can run is z/OS (MVS). Within z/OS it can run in many environments such as batch, CICS, USS and TSO. If you want to use TSO services, you must be running under TSO (not IRXJCL).
* TSO is the underlying foundation to the user 3270 and command interfaces for MVS. When you sign on to a terminal with your TSO id, you are using TSO. Similarly, when you run IKJEFT01 (or IKJEFT1A, etc) in batch you are also running TSO. Rexx can run outside of TSO but if you want to use TSO commands like ALLOC, FREE, DELETE, etc. you need to be running in a TSO address space and invoke the Rexx exec from TSO.
* ISPF is an add-on that runs under TSO. It has its own set of services for doing things like editing files, displaying panels and the like. It requires TSO but has its own programmable services accessed in Rexx via Address ISPEXEC. ISPF services can also be accessed through most other programming languages (COBOL, Assembler, C, APL, etc) but ISPF, and hence TSO must be there too.
It is very common to see questions phrased as "I am new to Rexx... how do I do <ISPF thing>"? They are not the same thing (though you can usually use Rexx to tell ISPF to do <ISPF thing>. It may seem like a picky detail, but if you want to find out where to look for answers, you need to know what component does what you are looking for.
One other misconception about ISPF is that it is driven only by CLISTs or Rexx. I often see people say 'look for the CLIST that drives option X" and that is often good advice, but very rarely is IBM or other vendor code written in Rexx. Usually it is a compiled program in COBOL or Assembler so looking for source is not helpful.
|
|
|
