sstack
} *sstack;
sstack = (struct sstack *)calloc(maxfiles, sizeof(struct sstack));
if (sstack == NULL) {
sstack[++ssp].s_file = input;
sstack[ssp].s_cond = cond;
sstack[ssp].s_loading = loading;
cond = sstack[ssp].s_cond;
loading = sstack[ssp].s_loading;
input = sstack[ssp--].s_file;