pthread_attr_setguardsize - Changes the guardsize
attribute of the specified thread attributes object
size_t guardsize );
DECthreads POSIX 1003.1c Library (libpthread.so)
Interfaces documented on this reference page conform to
industry standards as follows:
IEEE Std 1003.1c-1995, POSIX System Application Program
Address of the thread attributes object whose guardsize
attribute is to be modified. New value for the guardsize
attribute of the thread attributes object specified by
This routine uses the value specified in the guardsize
argument to set the guardsize attribute of the thread
attributes object specified in the attr argument.
When creating a thread, use a thread attributes object to
specify nondefault values for thread attributes. The
guardsize attribute of a thread attributes object specifies
the minimum size (in bytes) of the guard area for the
stack of a new thread.
A guard area, with its associated overflow warning area,
can help a multithreaded program detect overflow of a
thread's stack. A guard area is a region of no-access memory
that DECthreads allocates at the overflow end of the
thread's stack, following the thread's overflow warning
area. If any thread attempts to write in the overflow
warning area, a stack overflow exception occurs. Your program
can catch this exception and continue processing as
long as the thread does not attempt to write in the guard
area. When any thread attempts to access a memory location
within the guard area, a memory addressing violation
occurs without the possibility of recovery.
A new thread can be created with a default guardsize
attribute value. This value is platform dependent, but
will always be at least one "hardware protection unit"
(that is, at least one page). For more information, see
the platform-specific appendixes of Guide to DECthreads.
After this routine is called, due to platform-specific
factors DECthreads might reserve a larger guard area for
the new thread than was specified in the guardsize argument.
For more information, see the platform-specific
appendixes of Guide to DECthreads.
DECthreads allows your program to specify the size of a
thread stack's guard area for two reasons: When a thread
allocates large data structures on its stack, a guard area
with a size greater than the default size might be
required to detect stack overflow. Overflow protection of
a thread's stack can potentially waste system resources,
such as for an application that creates a large number of
threads that will never overflow their stacks. Your multithreaded
program can conserve system resources by "turning
off" a thread's stack guard area--that is, by specifying a
guardsize attribute of zero.
If a thread is created using a thread attributes object
whose stackaddr attribute is set (using the
pthread_attr_setstackaddr(3) routine), this routine
ignores the object's guardsize attribute and provides no
thread stack guard area for the new thread.
If an error condition occurs, this routine returns an
integer value indicating the type of error. Possible
return values are as follows: Successful completion. The
argument attr is not a valid thread attributes object, or
the argument guardsize contains an invalid value.
Functions: pthread_attr_init(3), pthread_attr_getguardsize(3), pthread_attr_setstacksize(3), pthread_create(3)
Manuals: Guide to DECthreads and Programmer's Guide
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