A file stack is multiple sets of fixed‑length, logical records, stored in a single, physical scratch file. These logical record sets are organized in the file in a last‑in, first‑out (LIFO) stack manner. A file stack enables you to “stack” temporary files, rather than maintaining multiple files individually.
File stacks are maintained by the Toolkit file‑stack subroutines. These routines are used by Toolkit’s list processor, and can be called from your applications as well.