What about TSO?
On Jul 31, 2012, at 10:17, Steve Comstock wrote:
>>>
>> We're both familiar with UNIX, which classically runs each process in
>> a separate address space. How much simpler or more effective
>> could it be? Likewise z/VM.
>
> Yes, well, each batch job runs in a separate address space, too.
> Isn't that the same approach?
> ...
> But for basic applications (batch and TSO, most CICS and IMS), the
> application programmer has his/her storage protected from meddling by
> other applications automatically by address space isolation.
>
Not really. You're ignoring the convolutions TSO performs to
execute an authorized program such as IEBCOPY (well, prior
to 1.13). Why can't TSO just launch IEBCOPY in a separate
address space where it would be perfectly safe? Why are
programmers compelled to invent "magic" SVCs and back doors?
Why can't TSO CLISTs and EXECs run commands in background
as I can with POSIX shell "&", and let me use my terminal
in the meantime?
Submitting to a batch queue is a stopgap. There's no simple
and standard way to get completion status from a program
submitted to a batch queue, or even to tell when it completes.
With POSIX shell, it's as simple as:
( command1; command2 ) &
PID=$!
# ... Do other stuff with terminal session
wait $PID
echo $? # display status from "command2"
command1 and command2 are completely isolated from the terminal
session and, if _BPX_SHAREAS=NO, from each other. In z/OS,
I can't even run an authorized program from an EXEC except with
severe constraints:
o It must be under TSO, not USS or IRXJCL
o It must be invoked with CALL, not ATTCHMVS or LINKMVS.
UNIX provides isolation for interactive commands similar
to that z/OS provides for batch jobs.
-- gil
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