>So my current fundamental question is: what identifies an address space 
>besides the ASID?
The STOKEN is the only thing that uniquely identifies an address space for the 
life of the IPL.

>That is, I would have thought that ASID X'1234' meant the same address space, 
>whoever referred to it. An address space might be refused access to it, but 
>would always mean the same one no matter who referred to it. Is this incorrect?

I recently encountered a situation where one tcb in a server had started an 
address space with asid 1234, which immediately terminated with a JCL error. 
Another tcb in the same server had also started an address space in the correct 
timeframe to *also* get asid 1234. This STC actually started up and stayed up. 
Both TCBs later believed to be talking each to its own address space, when in 
essence both TCBs were talking to the same one that had the asid sequentially 
after the first terminated.

So asid is not a unique criterium to identify an address space, but STOKEN is. 
You get the STOKEN either from the ASCRE invocation or by using LOCASCB to 
translate asid into STOKEN. In the latter case, beware that until LOCASCB 
returns, the asid may already be the wrong one due to the slot in the ASVT 
getting reused by the next request.

Barbara

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