We may have lost the original thread on this topic? Writing a macro to simulate the actions of a new (but not universally available) instruction has several merits:
(1) The macro can directly emulate the new instruction, or call an internal or external subroutine; the macro-generated code can be debugged and tested on its own without requiring testing the entire application that uses it. (2) Knowing the properties of the end-user's system means you can ship a version of the application with a simple reassembly that accounts for the presence or not of the new instruction. (3) Fortunately, useful new instructions appear in groups, so a simple SYSPARM or global variable symbol value can determine which of possibly many such macros should expand to use emulation or the new instruction. John Ehrman
