BIG              2105 user/usertests.c   amt = BIG - (uint64)a;
BIG              2113 user/usertests.c   lastaddr = (char *)(BIG - 1);
BIG              2221 user/usertests.c       if (sbrk(BIG - (uint64)sbrk(0)) == (char *)SBRK_ERROR)
BIG              2261 user/usertests.c     a = sbrk(10 * BIG);
BIG              2265 user/usertests.c     printf("%s: allocate a lot of memory succeeded %d\n", s, 10 * BIG);