Is there any use for this function at all? What is the concept of "last allocated byte", from the lisp point of view? Is the returned value large or small? There is no concept of "total available bytes", for example. (memory-limit) => 33756 33756 peanuts? My xemacs is currently only 8620K private committed. The problem is that I do not know the address of "first allocated byte" :) I propose to delete this function altogether. Big K DEFUN ("memory-limit", Fmemory_limit, 0, 0, "", /* Return the address of the last byte Emacs has allocated, divided by 1024. This may be helpful in debugging Emacs's memory usage. The value is divided by 1024 to make sure it will fit in a lisp integer. */ ()) { return make_int ((EMACS_INT) sbrk (0) / 1024); }