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These routines deal with the stack of variables.
Show the contents of the stack.
Pop values from the stack.
Push values on the stack.
PUSH,a,b pushes a and b onto the stack in that
order, so that b ends up on top of the stack. The contents of
the stack are listed in reverse order of pushing (i.e., the last pushed
one is listed first) by dump_stack. The pop routine pops
values from the stack. Arguments to pop that are named variables
receive successive values from the stack, so that after PUSH,a,b,
POP,c,d restores the pushed value of a into c, and
the pushed value of b into d. Arguments that are unnamed
must reduce to a number, and that number of values are then popped from
the stack into their original named source variables. So, after
PUSH,a,b, POP,2 restores a and b from the
stack. If you want to restore the number of elements that is contained
in a named variable n, then use POP,NUM=n. An argument to
keyword num is always treated first.
You can mix named variables and unnamed values in the argument list of
pop. Named variables are treated in blocks, unnamed values are
treated one by one. For example, POP,a,b,3,c,d,e restores first
to b, then to a, then three elements to their original
sources, then to e, then to d, and finally to c.