What are these error codes in C++ program?

I am using WinApi and playing with codes in my own ways. I have this program with such structures. Here I am creating FCOORD to store floating coordinates value of my (x,y) axis. Next is a circle structure that have center coordinates and radius.

typedef struct _FCOORD{
   int x;
   int y;
}FCOORD,*PFCOORD;

typedef struct _circle{
   float radius;
   FCOORD center;
}circle;

In my main() function I have dynamically allocated the memory.

int main(){
   int circleCount=0;
   float defRad=10.00f;
   circle **circ;
   circ=(circle **)malloc(sizeof(circle *));
   circ[circleCount]=(circle *)malloc(sizeof(circle));

   while(1){
      if(key[VK_LBUTTON]){
          circ[circleCount]->center=GetMouseCoord(); //Here GetMouseCoord() has FCOORD return type
          circ[circleCount]->radius=defRad;
          
          //Now I allocate memory for other circle.
          circleCount++;
          circ[circleCount]=(circle *)malloc(sizeof(circle));
          
          printf("No. of Circles: %d\n",circleCount);
      }
      
      /*
       *     I have functions that display values in Console.
       *
       *
       */
   }

}

Here it works but after about 287 circles the program crashes and shows this error code.

No of Circles : 287
make: *** [run] Error -1073740286

I thought that may be case of stack memory running out so I globalized it to use the heap instead.

circle **circ;

int main(){
    /*
     *
     */
    circ=(circle **)malloc(sizeof(circle *));
    circ[circleCount]=(circle *)malloc(sizeof(circle));
    /*
     *
     */
}

I can now pump out about 673 then it crashes.

No of Circles : 673
make: *** [run] Error -1073741819

Is this problem memory related or is there other things that I have been missing in my code.

ALSO: I found that it usually crashes when I return to the program window after clicking outside when using the globalizing method.

EDIT: Many are saying that this program is just for C, not C++. Well, I am using both codes with winapi and have compiled the whole code with g++. So my whole program is C++ based and only this particular part is code using C. And this error code I don't know if it is from C code part or my other bigger code.

Thanks Sammy1410