Itanium® Architecture for Programmers: Understanding 64-Bit Processors and EPIC Principles

Chapter 7

A1:	The application programmer is probably most interested in the more deeply stacked information that is out of scope at the point where interactive debugging is currently concentrated; such information was presumably deposited by program modules higher up through a calling tree that resulted in the current program state. This is also primarily the case if a system program crashes, but there could be some value in inspecting “high-water” depositions on the stack, just as a geologist only learns about large ancient floods by looking at the eroded high banks of a river.
A2:	Zero would be a valid digit value, but a negative value could be used as the flag and be easily tested. How?
A3:	Register r11 serves as the pointer for the user stack. ...