Well, the problem is that my program crashes abruptly when trying to create a dynamic matrix of 131072*(131072*2) if I try 16384*(16384*2+2) it still works fine. So I need a way to create the matrix without the program crashing.
int ROW=b_len; //131072
int COL=a_len+b_len+OVERFLOW; //131072*2+2
int** mat = new int*[ROW];
printf("\n\nHURRA"); //It prints this
for (int i = 0; i < ROW; ++i) //I think it crashes here
mat[i] = new int[COL];
printf("\n\nolv"); //But not this