| PTHREAD_ATTR_GETGUARDSIZE(3) | Library Functions Manual | PTHREAD_ATTR_GETGUARDSIZE(3) | 
pthread_attr_getguardsize,
  pthread_attr_setguardsize —
#include <pthread.h>
int
  
  pthread_attr_getguardsize(const
    pthread_attr_t * restrict attr,
    size_t * restrict
    guardsize);
int
  
  pthread_attr_setguardsize(pthread_attr_t
    *attr, size_t
    guardsize);
pthread_attr_getguardsize() and
  pthread_attr_setguardsize() functions get and set
  guardsize in the attr object. If
  guardsize is larger than 0, the system reserves an
  additional region of guarded memory of at least
  guardsize bytes at the end of the thread's stack for
  each new thread created by using attr.
The guarded area is understood to be pages of memory that are protected from read and write access. While the guarded area should be rounded by the system page size, the actual default size is implementation-defined. In NetBSD the default guardsize is given by the vm.thread_guard_size sysctl(7).
The rationale behind guardsize is two-fold:
SIGSEGV signal or experience other comparable
      fatal error condition. Note that if a thread allocates large data
      structures on stack, it may be necessary to raise the default
      guardsize in order to detect stack overflows.If pthread_attr_setstack(3) or pthread_attr_setstackaddr(3) is used to set the stack address attribute in attr, the guard size attribute is ignored and no guard area will be allocated; it is the responsibility of the application to handle the overflow conditions.
pthread_attr_getguardsize().
The pthread_attr_setguardsize() may fail
    if:
ENOMEM]| July 2, 2017 | NetBSD 9.3 |