USRSTACK
#define PS_STRINGS (USRSTACK - sizeof(struct ps_strings))
usrstack = (char *)USRSTACK;
USRSTACK - PAGESIZE, USRSTACK - PAGESIZE, &proc_stack_ops);
#define USRTEXT USRSTACK
#define MAXSSIZ (USRSTACK - 1024*1024)
#define DFLSSIZ (8*1024*1024 + ((USRSTACK) & 0x3FFFFF))
#define USRSTACK32 USRSTACK
#define USRSTACK64_32 USRSTACK