pthread_attr_setstack(3C) Syntax

int pthread_attr_setstack(pthread_attr_t *tattr,void *stackaddr, size_t stacksize);

#include <pthread.h> 
#include <limits.h>
pthread_attr_t tattr; 
void *base; 
size_t size; 
int ret; 
base = (void *) malloc(PTHREAD_STACK_MIN + 0x4000); 
/* setting a new address and size */ 
ret = pthread_attr_setstack(&tattr, base,PTHREAD_STACK_MIN + 0x4000);

The stackaddr attribute defines the base (low address) of the thread's stack. The stacksize attribute specifies the size of the stack. If stackaddr is set to non-null, rather than the NULL default, the system initializes the stack at that address, assuming the size to be stacksize.

base contains the address for the stack that the new thread uses. If base is NULL, then pthread_create(3C) allocates a stack for the new thread with at least stacksize bytes.