THR_MIN_STACK(3C) Standard C Library Functions THR_MIN_STACK(3C)

NAME

thr_min_stack - return the minimum-allowable size for a thread's stack

SYNOPSIS

cc -mt [ flag... ] file...[ library... ]
#include <thread.h>

size_t thr_min_stack(void);

DESCRIPTION

When a thread is created with a user-supplied stack, the user must
reserve enough space to run this thread. In a dynamically linked
execution environment, it is very hard to know what the minimum stack
requirements are for a thread. The function thr_min_stack() returns the
amount of space needed to execute a null thread. This is a thread that
was created to execute a null procedure. A thread that does something
useful should have a stack size that is thr_min_stack() + <some
increment>.


Most users should not be creating threads with user-supplied stacks. This
functionality was provided to support applications that wanted complete
control over their execution environment.


Typically, users should let the threads library manage stack allocation.
The threads library provides default stacks which should meet the
requirements of any created thread.


thr_min_stack() will return the unsigned int THR_MIN_STACK, which is the
minimum-allowable size for a thread's stack.


In this implementation the default size for a user-thread's stack is one
mega-byte. If the second argument to thr_create(3C) is NULL, then the
default stack size for the newly-created thread will be used. Otherwise,
you may specify a stack-size that is at least THR_MIN_STACK, yet less
than the size of your machine's virtual memory.


It is recommended that the default stack size be used.


To determine the smallest-allowable size for a thread's stack, execute
the following:

/* cc thisfile.c -lthread */
#define _REENTRANT
#include <thread.h>
#include <stdio.h>
main() {
printf("thr_min_stack() returns %u\n",thr_min_stack());
}

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|MT-Level | MT-Safe |
+---------------+-----------------+

SEE ALSO

attributes(7), standards(7)

November 26, 2017 THR_MIN_STACK(3C)