You'll have to spell it as ETXR, and if by "offset" you mean offset
from 0, then sure.

You can do what you want with the registers.  The ETXR runs under an
IRB on the mother task, so I'm not sure why any of them need to be
saved.

Beyond that, I've no idea what you're planning on doing, but ETXRs
aren't normally suitable for doing much.


sas

On Tue, Aug 29, 2017 at 9:02 AM, Binyamin Dissen
<[email protected]> wrote:
> As I believe that it gets control via SYNCH(X), you really do not need to save
> or restore any registers. Just exit by branching to the address that was
> contained in R14 when entered.
>
> It would be a bit of an integrity exposure for the task termination routine to
> trust your registers.
>
> On Tue, 29 Aug 2017 06:02:12 -0400 Thomas David Rivers <[email protected]>
> wrote:
>
> :>When you specify the EXTR= parameter on an ATTACH, you
> :>are indicating the offset of an exit to asynchoronously receive
> :>control when the sub-task ends.
> :>
> :>This exit is invoked as many are, in that a 72-byte save area
> :>is addressed by R13 for saving/restoring the registers.
> :>
> :>The documentation even goes on to say:
> :>
> :> "The exit routine is responsible for saving and restoring
> :>   registers".
> :>
> :>In the 'MVS Programming: Assembler Services Guide" in the
> :>section on linkage, called "Saving the calling program's registers"
> :>it says that saving registers involves saving R2 through R13
> :>"Unless otherwise defined by the individual interface".
> :>
> :>Has the one sentence in the EXTR description 'otherwise defined'
> :>that R14,R15,R0 and R1 also need to be saved; or is it referring
> :>tot he normal saving which would not preserve those?  It seems
> :>a little ambiguous to me.
> :>
> :>That is - in the case for an EXTR exit - do we need to also save/restore
> :>R14,R15,R0 and R1 - or are those "safe" to trash?  I'd like to use
> :>them to trampoline into a different environment if possible without
> :>having to do a "save-area dance".
> :>
> :>   - Thanks -
> :>   - Dave Rivers -
>
> --
> Binyamin Dissen <[email protected]>
> http://www.dissensoftware.com
>
> Director, Dissen Software, Bar & Grill - Israel
>
>
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> you should preauthorize the dissensoftware.com domain.
>
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> especially those from irresponsible companies.
>
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sas

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