Header File 

malloc.h  

Category 

Memory Routines 

Prototype 

size_t stackavail(void); 

Description 

Gets the amount of available stack memory. 

stackavail returns the number of bytes available on the stack. This is the amount of dynamic memory that alloca can access. 

Return Value 

stackavail returns a size_t value indicating the number of bytes available. 

Example  

 #include <malloc.h>
 #include <stdio.h>
 
 int main(void) 
 {
   char *buf;
 
   printf("\nThe stack: %u\tstack pointer: %u", stackavail(), _SP);
   buf = (char *) alloca(100 * sizeof(char));
   printf("\nNow, the stack: %u\tstack pointer: %u", stackavail(), _SP);
   return 0;
 }

Portability