AT&T 6300 Programmer's Manual page 635

stack pointer
Advanced Features
high
addresses argument 0
argument 1
Absent if any argument is
referenced within a nested
procedure
c
s
0
argument n
t
u
a n
c t return segment address Absent in local procedure
k
e
r return offset
~
low
addresses
local variables
(data pushed on
stack)
This space may be
used during pro-
cedure execution
(SP register
contents)
~
Stack pointer may change
during procedure
execution
Stack Layout During Execution of a CALL Statement
B-9