Interesting. That makes sense. I've got a better method anyway, but you know
what IBM says now? I just happened to run into this a few minutes ago. (From
the Nov. 2012 PoOp)

Programming Note: Prior to the introduction of
z/Architecture, determination of the presence of a
facility was often accomplished by means of a trial
execution of an instruction. If an operation exception
was not recognized during the trial execution, then it
could be assumed that the facility was present.

Similarly, certain instructions provide a query function
to determine the availability of other functions of
the instruction or related instructions. However, a
program might attempt to determine the availability of
a particular function by trial execution of the function.

With the advent of facility and function indications in
z/Architecture, the technique of trial execution should
be avoided - particularly if a workload may be relocated
to another system in which a facility's instructions
may not be present. In such an environment,
STORE FACILITY LIST EXTENDED (STFLE) or an
instruction's query or test function may provide a
more accurate indication of facilities and functions
that are available on all systems in the computing
environment.

Charles

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