<snip>
LA 1,1(0)
ST 1,AXNUM
AXRES AXLIST=AXL GET AN EAX FOR SERVICE1 (THE X
PC ROUTINE)
L 4,AXVAL
</snip>
FWIW, changing the L to a LH works fine in the example, even if AXVAL
happens to have its high bit on, because in the example reg 4 is used only
as the operand on ETDEF of "EAX=(4)" which is a 2-byte operand and does
"STH".
The contents of bits 0-15 of 32-bit GR 4 do not affect the processing.
In "general", you'd probably choose to use instruction(s) that made sure
that sign bit propagation would not adversely affect you.
In practice, although I didn't check, a system might never land with an AX
>= 32K (the case where the AX has the high bit on).
Of course, as has been pointed out, the "ST" needs to be "STH".
Peter Relson
z/OS Core Technology Design
