GALLOC(3)                                               GALLOC(3)

     NAME
          galloc, gfree, garbage - storage allocation with garbage
          collection

     SYNOPSIS
          char *galloc(n)
          unsigned n;

          gfree(p)
          char *p;

          garbage( )

     DESCRIPTION
          These functions perform heap storage allocation with garbage
          collection.

          Galloc allocates a block of at least n bytes and returns a
          pointer to it.  Gfree frees a block previously allocated by
          galloc.

          When space gets tight, garbage blocks are freed automati-
          cally.  A block allocated by galloc is deemed to be garbage
          unless it is reachable.  A reachable block is one whose
          first byte is pointed to by a declared C variable or by a
          pointer in a reachable block.

          The frequency of garbage collection is controlled by exter-
          nal variables declared

               long gcmax = 5000, gcmin = 50;

          No more than gcmax allocations may intervene between auto-
          matic collections; this feature will help contain the growth
          of virtual address space.  At least gcmin allocations must
          intervene, otherwise garbage collection will be abandoned as
          fruitless.  Garbage may be called to do garbage collection
          at an arbitrary time.

          Malloc(3) and galloc allocate from the same arena, but gar-
          bage collection affects only galloc blocks.  Free (see
          malloc(3)) must not be used on blocks allocated with galloc.

     DIAGNOSTICS
          Galloc returns a null (0) pointer when space cannot be
          found.

     SEE ALSO
          malloc(3)

     GALLOC(3)                                               GALLOC(3)

     BUGS
          Garbage collection is conservative; blocks that appear to be
          pointed to from within declared storage will not be freed,
          regardless of whether the apparent `pointers' were declared
          as such.