pthread_attr_getguardsize(3THR) gets the guardsize of the attr object.
A conforming implementation is permitted to round up the value contained in guardsize to a multiple of the configurable system variable PAGESIZE (see PAGESIZE in sys/mman.h). If an implementation rounds up the value of guardsize to a multiple of PAGESIZE, a call to pthread_attr_getguardsize() specifying attr will store, in guardsize, the guard size specified in the previous call to pthread_attr_setguardsize().
#include <pthread.h> int pthread_attr_getguardsize(const pthread_attr_t *attr, size_t *guardsize);
pthread_attr_getguardsize() fails if:
EINVAL
The argument attr is invalid, the argument guardsize is invalid, or the argument guardsize contains an invalid value.