recursive function in Cilk

Hello,

I just write a simple Cilk code to test how deep recursive function call Cilk can reach.  When I set up recursive level over 100,000, Cilk application has segmentation fault.  How do I extend recursive level to go deeper?  Or, how big the stacksize there is as default?

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Result:
[amos@Machine Pi]$ ./cilk-icc 100
Cilk took 0.000000 sec
Steps = 100.000000;Pi = 3.141601
[amos@Machine Pi]$ ./cilk-icc 1000
Cilk took 0.290000 sec
Steps = 1000.000000;Pi = 3.141593
[amos@Machine Pi]$ ./cilk-icc 10000
Cilk took 0.370000 sec
Steps = 10000.000000;Pi = 3.141593
[amos@Machine Pi]$ ./cilk-icc 100000
Segmentation fault (core dumped)

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Code:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <cilk/cilk.h>
#include <time.h>

static double num_steps;
double step, pi;
double pi_calculate( double counter, double sum );

static void _usage(FILE *f, int error) {
  fprintf(f, "Usage: ./cilk NUMBER\n");
  fflush(f);
}

int main(int argc, char *argv[])
{
    int i,j;
    double x, sum=0;

    argc -= optind;
    argv += optind;

    switch (argc) {
        case 0:
            fprintf(stderr, "\nMissing pi number.\n"); // fall through
        default:
            _usage(stderr, 0);
        case 1:
            num_steps = atof(argv[0]);
            break;
    }
    step = 1.0/ (double)num_steps;

    clock_t start = clock();
    sum = pi_calculate( 0, 0 );
    clock_t end = clock();

    double duration = (double)(end - start) / CLOCKS_PER_SEC;
    printf("Cilk took %f sec\n", duration);

    pi = step*sum;
    printf( "Steps = %f;Pi = %f\n", num_steps, pi );

    return 0;
}

double pi_calculate( double counter, double sum )
{
    double x, result=0, result_2=0;

//printf("counter =%f/%f\n", counter, num_steps);
    if( counter < num_steps ) {
        x = (counter + 0.5) * step;
        result = sum + 4.0/(1.0+x*x);
        result_2 = cilk_spawn pi_calculate( counter+1, result );
        cilk_sync;
        return result_2;
    }
    else return sum;
}

--

Amos