buffTwo

// From IBM and their ideas...

#define _XOPEN_SOURCE 500

#include <stdio.h>
#include <signal.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#ifdef __cplusplus
    extern "C" {
#endif

#ifdef __cplusplus
    }
#endif

int main(void) {
   FILE *fp;
   char buffer[80];
   int i = 0;

   fp = fopen("testfull.txt", "w+");
   if (fp == NULL) exit(99);

   memset(buffer, 'A', 80);

   /* write to MVS file until it runs out of extents */

   while (fwrite(buffer, 1, 80, fp) == 80)
      ++i;

   printf("number of successful fwrites of 80 bytes = %d\n", i);

   return 0;
}