pthread_attr_setguardsize_np - Changes the guardsize attribute of the specified thread attributes object.
DECthreads POSIX 1003.1c Library (libpthread.so)
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 attr.
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 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. When any thread attempts to access a memory location within this region, a memory addressing violation occurs.
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.
This routine has been superseded by the pthread_attr_setguardsize(3) routine, as specified by the Single UNIX Specification, Version 2.
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 invalid, or the argument guardsize contains an invalid value.
Functions: pthread_attr_init(3), pthread_attr_getguardsize_np(3), pthread_attr_setstacksize(3), pthread_create(3)
Manuals: Guide to DECthreads and Programmer's Guide