🚀 go-pugleaf

I was attempting to run a Quintus Prolog program that potentially generates
exponential number of clauses on the inputs. In my case, my set of clauses 
are roughly 200 where each clause is about 5 literals. They are represented 
by a list of lists. Unfortunately I ran into [segmentation fault] on a Sun4, 
SunOS 3.2. I suspected there is some problem with the memory management. I
decided to test the memory by writing the following simple program: 

  (1) an outer "loop" that run for "N" times; 
  (2) an inner loop that mutiply a list of 10 chars ['1234567890'] 
      for 18 times and never returns the list.

By calling "loop(300)" on the Sun4, the program crash and exits Quintus Prolog.

Questions: (a) Which stack has overflowed ?
           (b) In general, what are the factors to observe when writing
               prolog programs that takes up lots of memory. 

-------------------------------------------------------------------------
pair(0,_).
pair(N,X) :-
  append(X,X,Z1),
  N1 is N - 1,
  pair(N1,Z1).

loop(0).
loop(N) :-
  pair(18,['0123456789']),
  !, garbage_collect,
  J is N -1,
  loop(J).
-------------------------------------------------------------------------

Thanks.

Alex Kean
Department of Computer Science
University of British Columbia
Vancouver, British Columbia,
Canada.