Get and Set the stack size of thread attribute in C

To get and set the stack size of thread attribute in C, we use the pthread_attr_getstacksize() and pthread_attr_setstacksize() functions. These functions allow us to query and modify the minimum stack size allocated to a thread's stack.

Syntax

int pthread_attr_getstacksize(const pthread_attr_t *attr, size_t *stacksize);
int pthread_attr_setstacksize(pthread_attr_t *attr, size_t stacksize);

pthread_attr_getstacksize()

This function retrieves the current stack size from a thread attribute object. It returns 0 on success, otherwise returns an error number.

Parameters:

• attr − Pointer to the thread attribute object
• stacksize − Pointer to store the retrieved stack size in bytes

pthread_attr_setstacksize()

This function sets a new stack size for a thread attribute object. It returns 0 on success, otherwise returns an error number.

Parameters:

• attr − Pointer to the thread attribute object
• stacksize − New stack size in bytes to be set

Note: To compile and run this program, use: gcc program.c -lpthread

Example

Here's a complete example demonstrating how to get and set thread stack size −

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

int main() {
    size_t stacksize;
    pthread_attr_t attr;
    
    /* Initialize the thread attribute object */
    pthread_attr_init(&attr);
    
    /* Get current stack size */
    pthread_attr_getstacksize(&attr, &stacksize);
    printf("Default stack size = %zu bytes
", stacksize);
    
    /* Set new stack size */
    pthread_attr_setstacksize(&attr, 65536);
    
    /* Get the updated stack size */
    pthread_attr_getstacksize(&attr, &stacksize);
    printf("New stack size = %zu bytes
", stacksize);
    
    /* Destroy the attribute object */
    pthread_attr_destroy(&attr);
    
    return 0;
}

Default stack size = 8388608 bytes
New stack size = 65536 bytes

Key Points

• Always initialize thread attributes with pthread_attr_init() before use
• The stack size must be at least PTHREAD_STACK_MIN bytes
• Use %zu format specifier for size_t values in printf()
• Remember to destroy attribute objects with pthread_attr_destroy()

Conclusion

The pthread_attr_getstacksize() and pthread_attr_setstacksize() functions provide control over thread stack allocation. Proper stack size management is crucial for thread performance and memory usage in multithreaded applications.