NAME
pthread_default_stacksize_np() — change the default stacksize
SYNOPSIS
#include <pthread.h>
int pthread_default_stacksize_np(
size_t new_size,
size_t *old_size
);
PARAMETERS
- new_size
The new default stack size.
- old_size
Pointer to where the old default stack size is returned.
DESCRIPTION
The
pthread_default_stacksize_np()
function allows an application to change the default value for the
stacksize
attribute.
This function must be called before any threads have been created.
The new default stack size is passed in the
new_size
parameter. If not
NULL,
the previous default stack size is returned in
old_size.
If
new_size
is zero, this function can be used (at any time) to query the current
default stack size.
On HP-UX, threads with default stack sizes are cached after they terminate.
The next time a thread is created with a default stack size, a cached
thread (and its stack) are reused. This can result in significant
performance improvements for
pthread_create().
However, if the default stack size is not appropriate for an application,
it cannot take advantage of this performance enhancement. By using
the
pthread_default_stacksize_np()
function, the threads library will change
the default stack size so that it matches the applications needs.
This allows the application to utilize the performance benefit of
cached threads.
RETURN VALUE
Upon successful completion,
pthread_default_stacksize_np()
returns zero. Otherwise, an error number is returned to indicate the error
(the
errno
variable is not set).
ERRORS
If any of the following occur, the
pthread_default_stacksize_np()
function returns the corresponding error number:
- [EINVAL]
The value specified by
new_size
is less than
PTHREAD_STACK_MIN.
- [EPERM]
The calling process has already created threads (this must be called
before any threads are created).
WARNINGS
If the environment variable
PTHREAD_DEFAULT_STACK_SIZE
is set with a valid value for default stack size, then it takes
precedence over the invocation of
pthread_default_stacksize_np()
interface.
However, it returns the current default stack size in
old_size.
The maximum default stack size value that may be set through the
PTHREAD_DEFAULT_STACK_SIZE
environment variable is restricted to 10 MB; any value greater than
10 MB will be rounded down to 10 MB.
Care should be taken while setting the default stack
size limit since this could impact the maximum number of threads that can be
created in a process.
AUTHOR
pthread_default_stacksize_np()
was developed by HP.
SEE ALSO
pthread_attr_getstacksize(3T),
pthread_attr_setstacksize(3T).
STANDARDS CONFORMANCE
pthread_default_stacksize_np(): None.
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