compiling nethack on SCO xenix

[Ben Smith]

I have been trying to compile nethack on SCO (286 w/ 2Meg memory).
The problem is encountered when 'make -f Makefile.xenix' gets to
compiling the ttys module.

I get an error 
     /usr/include/sys/termio.h(45): fatal error 2: out of heapspace 
(I can't seem to force it to look at the termio.h in /usr/include/sys.)

Ideas for getting around the problem?  - anyone remember what had to
be done with this segmented machines?
-ben