BIG              2074 user/usertests.c   amt = BIG - (uint64)a;
BIG              2081 user/usertests.c   lastaddr = (char*) (BIG-1);
BIG              2188 user/usertests.c       if (sbrk(BIG - (uint64)sbrk(0)) ==  (char*)SBRK_ERROR)
BIG              2227 user/usertests.c     a = sbrk(10*BIG);
BIG              2231 user/usertests.c     printf("%s: allocate a lot of memory succeeded %d\n", s, 10*BIG);