does two recursive calls work simultaneously or one after the other?

so I was testing the recursive function , that is , will the function at first recursion , let the recursion complete and then proceed or will it simply initialize the recursion and proceed on , that is will both the recursive calls print numbers simultaneously or first it will print num to 1 and then it will print num to 100 ; anyway , my compiler is just outputing 32 infinitely when i give num as 23 ;

void print(int num){
   if(num == 1 || num == 100){
        return;
    }
    std::cout << num ;
    print(num-1);
    std::cout << std::endl;
    print(num+1);

    return;
}