On Mon, 4 Apr 2011 07:27:13 -0500, McKown, John wrote: >you'd need to look at the passed in save area to see if you were >supplied with one which has room for the upper half of the registers.
You can not tell by looking at the save area that was passed to you to determine the size of the save area that was passed to you. A program does not "determine". A program "requires". If your program requires a 144-byte save area, your callers must provide it. If you cannot control your callers, you have to operate on the assumption that you have only a 72-byte save area. The OP can simply save the high halves in his own storage if he chooses, but he should restore the high halves before returning to his caller. -- Tom Marchant
