You might note that the offsets to the local variables in this generated code are quite high, at 88 and 92 - much longer than a save area would typically be (13 fullwords, or 72 bytes - note the STM 14,12,12(R13) at the beginning). So, although I have not looked at this in any detail at all, I would guess that the first part of the local variable area allocated on the "stack" is the save area (pointed to by R13), and above that are local variables for the routine. It might have been easier to figure out had the sample code called another routine and you could see the call sequence from the caller's perspective.
cube1us