'\" t
.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH pthread_attr_setstacksize 3 2022-12-15 "Linux man-pages 6.03"
.SH NAME
pthread_attr_setstacksize, pthread_attr_getstacksize \- set/get stack size
attribute in thread attributes object
.SH LIBRARY
POSIX threads library
.RI ( libpthread ", " \-lpthread )
.SH SYNOPSIS
.nf
.B #include <pthread.h>
.PP
.BI "int pthread_attr_setstacksize(pthread_attr_t *" attr \
", size_t " stacksize );
.BI "int pthread_attr_getstacksize(const pthread_attr_t *restrict " attr ,
.BI "                              size_t *restrict " stacksize );
.fi
.SH DESCRIPTION
The
.BR pthread_attr_setstacksize ()
function sets the stack size attribute of the
thread attributes object referred to by
.I attr
to the value specified in
.IR stacksize .
.PP
The stack size attribute determines the minimum size (in bytes) that
will be allocated for threads created using the thread attributes object
.IR attr .
.PP
The
.BR pthread_attr_getstacksize ()
function returns the stack size attribute of the
thread attributes object referred to by
.I attr
in the buffer pointed to by
.IR stacksize .
.SH RETURN VALUE
On success, these functions return 0;
on error, they return a nonzero error number.
.SH ERRORS
.BR pthread_attr_setstacksize ()
can fail with the following error:
.TP
.B EINVAL
The stack size is less than
.B PTHREAD_STACK_MIN
(16384) bytes.
.PP
On some systems,
.\" e.g., MacOS
.BR pthread_attr_setstacksize ()
can fail with the error
.B EINVAL
if
.I stacksize
is not a multiple of the system page size.
.SH VERSIONS
These functions are provided since glibc 2.1.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR pthread_attr_setstacksize (),
.BR pthread_attr_getstacksize ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH STANDARDS
POSIX.1-2001, POSIX.1-2008.
.SH NOTES
For details on the default stack size of new threads, see
.BR pthread_create (3).
.PP
A thread's stack size is fixed at the time of thread creation.
Only the main thread can dynamically grow its stack.
.PP
The
.BR pthread_attr_setstack (3)
function allows an application to set both the size and location
of a caller-allocated stack that is to be used by a thread.
.SH BUGS
As at glibc 2.8,
if the specified
.I stacksize
is not a multiple of
.B STACK_ALIGN
(16 bytes on most architectures), it may be rounded
.IR downward ,
in violation of POSIX.1, which says that the allocated stack will
be at least
.I stacksize
bytes.
.SH EXAMPLES
See
.BR pthread_create (3).
.SH SEE ALSO
.BR getrlimit (2),
.BR pthread_attr_init (3),
.BR pthread_attr_setguardsize (3),
.BR pthread_attr_setstack (3),
.BR pthread_create (3),
.BR pthreads (7)