Anonymous memory being created without any dynamic memory allocation

Hi

I was running the following code in BF609 with buildroot distribution. When I see the maps of this process, I found 3 regions of anonymous memory. I haven't done any dynamic memory allocation in my code. Can you kindly explain me why these regions are present and why are they created. How can the size of these anonymous regions be changed/controlled.

#include<stdio.h>

int a[4100000],b[4100000],d,e;

int main()

{

int i;

a[0]=1;

for(i=0;i<4100000;i++)

{

a[i+1]=a[i]+1;

b[i]=a[i];

}

d=b[4100000];

e=d;

return 0;

}

Maps for this process is attached.