Help me how to avoid stack over flow error in c++

First code.

#include <iostream>
using    namespace std;
void f(int k) 
{  
     if (k==100000) 
     { cout << a << endl; return; } 
     f(k+1); } 
int main() 
{ 
    int a = 1;
    freopen("out.txt","w",stdout); 
    f(1); 
    return 0; 
}

Second code.

#include <iostream>
using    namespace std;
void f(int k) 
{  
     int a = 1;
     if (k==100000) 
     { cout << a << endl; return; } 
     f(k+1); } 
int main() 
{ 
    freopen("out.txt","w",stdout); 
    f(1); 
    return 0; 
}

the second code gives stack over flow error .
Can anyone explain me how to modify stack memory ?