On Mon, 13 Mar 2017 15:29:30 -0400, Tony Harminc wrote:

>On 13 March 2017 at 15:10, Tom Marchant
><[email protected]> wrote:
>>
>> There isn't much that these stubs can do to figure out what PC to
>> issue without using any registers.
>
>They can use 0, 1, 14, 15. And "General and access registers 0, 1, 14,
>and 15 are not restored", so they can clobber those too.

Those are MVS linkage conventions. In XPLINK, 1 to 3 are for 
arguments, and 8-15 are "preserved"

>> In any case, R14 is the return address. That is standard linkage, not XPLINK.
>
>How does XPLINK know where to return to?

Register 7.
Register 6 might contain the entry point address. 
Or not if the routine was entered via BRAS.

-- 
Tom Marrchant

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