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.TH PTHREAD_ATTR_SETSTACK 3 2017-09-15 "Linux" "Linux Programmer's Manual"

.SH NAME

pthread_attr_setstack, pthread_attr_getstack \- set/get stack

attributes in thread attributes object

.SH SYNOPSIS

.nf

.B #include <pthread.h>

.PP

.BI "int pthread_attr_setstack(pthread_attr_t *" attr ,

.BI "                          void *" stackaddr ", size_t " stacksize );

.BI "int pthread_attr_getstack(const pthread_attr_t *" attr ,

.BI "                          void **" stackaddr ", size_t *" stacksize );

.PP

Compile and link with \fI\-pthread\fP.

.fi

.PP

.in -4n

Feature Test Macro Requirements for glibc (see

.BR feature_test_macros (7)):

.in

.PP

.ad l

.BR pthread_attr_getstack (),

.BR pthread_attr_setstack ():

.RS 4

_POSIX_C_SOURCE\ >=\ 200112L

.RE

.ad b

.SH DESCRIPTION

The

.BR pthread_attr_setstack ()

function sets the stack address and stack size attributes of the

thread attributes object referred to by

.I attr

to the values specified in

.IR stackaddr

and

.IR stacksize ,

respectively.

These attributes specify the location and size of the stack that should

be used by a thread that is created using the thread attributes object

.IR attr .

.PP

.I stackaddr

should point to the lowest addressable byte of a buffer of

.I stacksize

bytes that was allocated by the caller.

The pages of the allocated buffer should be both readable and writable.

.PP

The

.BR pthread_attr_getstack ()

function returns the stack address and stack size attributes of the

thread attributes object referred to by

.I attr

in the buffers pointed to by

.IR stackaddr

and

.IR stacksize ,

respectively.

.SH RETURN VALUE

On success, these functions return 0;

on error, they return a nonzero error number.

.SH ERRORS

.BR pthread_attr_setstack ()

can fail with the following error:

.TP

.B EINVAL

.I stacksize

is less than

.BR PTHREAD_STACK_MIN

(16384) bytes.

On some systems, this error may also occur if

.IR stackaddr

or

.IR "stackaddr\ +\ stacksize"

is not suitably aligned.

.PP

POSIX.1 also documents an

.BR EACCES

error if the stack area described by

.I stackaddr

and

.I stacksize

is not both readable and writable by the caller.

.SH VERSIONS

These functions are provided by glibc since version 2.2.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lbw24 lb lb

l l l.

Interface	Attribute	Value

T{

.BR pthread_attr_setstack (),

.BR pthread_attr_getstack ()

T}	Thread safety	MT-Safe

.TE

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008.

.SH NOTES

These functions are provided for applications that must ensure that

a thread's stack is placed in a particular location.

For most applications, this is not necessary,

and the use of these functions should be avoided.

(Use

.BR pthread_attr_setstacksize (3)

if an application simply requires a stack size other than the default.)

.PP

When an application employs

.BR pthread_attr_setstack (),

it takes over the responsibility of allocating the stack.

Any guard size value that was set using

.BR pthread_attr_setguardsize (3)

is ignored.

If deemed necessary,

it is the application's responsibility to allocate a guard area

(one or more pages protected against reading and writing)

to handle the possibility of stack overflow.

.PP

The address specified in

.I stackaddr

should be suitably aligned:

for full portability, align it on a page boundary

.RI ( sysconf(_SC_PAGESIZE) ).

.BR posix_memalign (3)

may be useful for allocation.

Probably,

.IR stacksize

should also be a multiple of the system page size.

.PP

If

.I attr

is used to create multiple threads, then the caller must change the

stack address attribute between calls to

.BR pthread_create (3);

otherwise, the threads will attempt to use the same memory area

for their stacks, and chaos will ensue.

.SH EXAMPLE

See

.BR pthread_attr_init (3).

.SH SEE ALSO

.ad l

.nh

.BR mmap (2),

.BR mprotect (2),

.BR posix_memalign (3),

.BR pthread_attr_init (3),

.BR pthread_attr_setguardsize (3),

.BR pthread_attr_setstackaddr (3),

.BR pthread_attr_setstacksize (3),

.BR pthread_create (3),

.BR pthreads (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.