last-in first-out

stack
FILO
last-in first-out
LIFO

   <programming> (See below for synonyms) A data structure for
   storing items which are to be accessed in last-in first-out
   order.

   The operations on a stack are to create a new stack, to "push"
   a new item onto the top of a stack and to "pop" the top item
   off.  Error conditions are raised by attempts to pop an empty
   stack or to push an item onto a stack which has no room for
   further items (because of its implementation).

   Most processors include support for stacks in their
   {instruction set architectures}.  Perhaps the most common use
   of stacks is to store {subroutine} arguments and return
   addresses.  This is usually supported at the {machine code}
   level either directly by "jump to subroutine" and "return from
   subroutine" instructions or by {auto-increment} and
   auto-decrement {addressing modes}, or both.  These allow a
   contiguous area of memory to be set aside for use as a stack
   and use either a special-purpose {register} or a general
   purpose register, chosen by the user, as a {stack pointer}.

   The use of a stack allows subroutines to be {recursive} since
   each call can have its own calling context, represented by a
   stack frame or {activation record}.  There are many other
   uses.  The programming language {Forth} uses a data stack in
   place of variables when possible.

   Although a stack may be considered an {object} by users,
   implementations of the object and its access details differ.
   For example, a stack may be either ascending (top of stack is
   at highest address) or descending.  It may also be "full" (the
   stack pointer points at the top of stack) or "empty" (the
   stack pointer points just past the top of stack, where the
   next element would be pushed).  The full/empty terminology is
   used in the {Acorn Risc Machine} and possibly elsewhere.

   In a list-based or {functional language}, a stack might be
   implemented as a {linked list} where a new stack is an empty
   list, push adds a new element to the head of the list and pop
   splits the list into its head (the popped element) and tail
   (the stack in its modified form).

   At {MIT}, {pdl} used to be a more common synonym for stack,
   and this may still be true.  {Knuth} ("The Art of Computer
   Programming", second edition, vol. 1, p. 236) says:

     Many people who realised the importance of stacks and queues
     independently have given other names to these structures:
     stacks have been called push-down lists, reversion storages,
     cellars, dumps, nesting stores, piles, last-in first-out
     ("LIFO") lists, and even yo-yo lists!

   [{Jargon File}]

   (1995-04-10)