On Sun, 7 Sep 2025 18:19:47 -0400, Mike Shaw <[email protected]> wrote:

>ISPF multi-tasks under TSO/E - The TMP IKJEFT01 attaches IKJEFT09 which
>attaches ISPMAIN which attaches ISPTASK, and each logical screen under ISPF
>
>If you want to write a multi-tasking ISPF application, you can. There are no 
>restrictions.

I'm sorry you felt insulted. I'm positive you would have realized there's a 
huge difference between multi-TCB and multi-tasking. 

For those who think Mike is talking about multi-tasking, I think the most 
common definition is 2 or more tasks running concurrently. Of the TCB's that 
Mike listed, will very rarely 2 be running at the same moment in time. Consider 
a split screen (2 ISPTASKs) where you issue a command on one of the screens and 
the physical screen is locked until the work is completed. You simply don't 
have the ability to issue a command from the command line. ISPF is not 
multi-tasking.

Alternatively, let's consider a single ISPTASK. ADDRESS ATTCHMVS creates a task 
but REXX waits for the task to terminate. No multi-tasking here.

My definition of "multi-tasking ISPF application" is 2 tasks doing ISPF things 
(not an ISPF application that has a subtask unrelated to ISPF activity). What 
happens if both tasks issue ISPEXEC DISPLAY at the same time with different 
display data. I suspect that ignores serialization because it's not needed in 
single active task design.

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