On Mon, 12 Aug 2013 10:37:44 -0600, Steve Comstock wrote: >On 8/12/2013 9:40 AM, Tom Marchant wrote: >> >> "F4SA" must be stored in the new save area. > >Really? "Must"? Is there anything that won't work correctly >if I omit that string? I think not.
What I meant was that when a program marks the format of the save area that it used to save its caller's registers, it must do so in the new save area, not in the caller's save area. Consider the case where A calls B, then B calls C. If B saved A's registers in standard 72-byte format, offset 4 of B's save area contains the address of A's save area. If C then saves B's registers in F4SA format, C marks its own save area with "F4SA". If it were to mark B's save area with "F4SA", then B would not be able to find the save area that it used to save A's registers. The only thing that won't work correctly if it is omitted is any program that has to follow the save areas to determine the calling sequence, such as a dump formatter. We rely on it in Abend-AID. -- Tom Marchant Abend-AID development Compuware
