On Mon, 11 Apr 2011 15:31:22 -0500, McKown, John wrote: >OK. So, in order to be totally safe when the programmer cannot >__guarantee__ that the caller has supplied a proper save area for >64 bit programs (i.e., the caller might or might not use the 72 >or 144 word save area format),
That's 72-byte (18 word) or 144 byte (18 doubleword) >then one __must__ assume a 72 work standard save area, no? In >which case, if called by a routine which uses 64 bit register How can you know what your callers do? If your caller does not use or alter the high halves, you _still_ have to restore the high halves if you use them. What if program A calls program B, which calls program C, which in turn calls you, and program A is the only one that cares about the high half of the registers? >save the low fullword of the registers in the save area. Then >save the high fullwords in an area the routine itself got That area could be in the form of F5SA, which was designed for this situation. -- Tom Marchant
