Objects leave the stack from level 1, and the objects remaining on the
stack each drop to a lower level. It's best to drop an object or store it
in a variable when you don't need it on the stack; this makes it easier
to keep track of the stack objects you do need. Similarly, it's best to
clear the entire stack when you begin a problem, so you'll know that
the objects on the stack are pertinent.
Viewing the Stack
Normally you see only the first few objects on the stack. If the object
in level 1 is large, you see only the first part of it. The operations
enable you to view the first part of any object
on the stack and all of the object in level 1.
These operations move the "window
through which you see the
stack. The size of this window can range from one to four display
lines, depending on the presence of a menu, the command line, or
Moves the window up (toward higher stack levels) .
Moves the window down (toward the end of the object in
Viewing has no effect on the contents of the stack, the command line,
or the action of commands.
Manipulating the Stack
In part 1 you used some basic commands for manipulating the stack:
CLEAR (to clear the stack), DROP (to drop the object in level 1), and
SWAP (to switch the order of the objects in levels 1 and 2). This sec-
tion briefly describes all commands for moving, copying, and
dropping stack objects; for details, see "STACK" in Reference Manual.
19: The Stack