[comp.lang.c] sbrk

rreiner@yunexus.YorkU.CA (Richard Reiner) (09/16/90)

I'm trying to use sbrk(negative_number) to persuade MS C 5.1 to give
some of its heap back to MS-DOS in a small model program so as to
leave more room for a spawn().  My little program is only about 20K of
code + 2K of data, but it seems to grab and keep a full 64K data
segment, thus reserving about 85K for itself during the spawn().

sbrk(negative_number) gives me an error return if negative_number <
-400; and calling sbrk() even with a small argument causes the spawn()
call a few lines later to fail.

Have I missed something, or is this just the usual MS-DOS foolishness?

--richard