program to calculate the largest year representable on a 64 bit system.

timemax.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <limits.h>
#define ONE_YEAR 60*60*24*366
int main(void)
{
        time_t now = 67767751872000000l;
        for(;;)
        {
                char * curtime = ctime(&now);
                if(!curtime)
                {
                        break;
                }
                printf("%s", curtime);
                printf("%ld\n", now);
                now += ONE_YEAR;
        }
        return EXIT_SUCCESS;
}