Data structures- stack using linked lists

#include<iostream>
#include<cstdlib>
using namespace std;

struct node
{
    int info;
    struct node *link;   
}*top;

class stack_list
{
    public:
        node *push(node *, int);
        node *pop(node *);
        void traverse(node *);
        stack_list()
        {
            top = NULL;
        }              
};

int main()
{
    int choice, item;
    stack_list sl;
    while (1)
    {
        cout<<"\n-------------"<<endl;
        cout<<"Operations on Stack"<<endl;
        cout<<"\n-------------"<<endl;
        cout<<"1.Push Element into the Stack"<<endl;
        cout<<"2.Pop Element from the Stack"<<endl;
        cout<<"3.Traverse the Stack"<<endl;
        cout<<"4.Quit"<<endl;
        cout<<"Enter your Choice: ";
        cin>>choice;
        switch(choice)
        {
        case 1:
            cout<<"Enter value to be pushed into the stack: ";
            cin>>item;
            top = sl.push(top, item);
            break;
        case 2:
            top = sl.pop(top);
            break;
        case 3:
            sl.traverse(top);
            break;
        case 4:
            exit(1);
            break;
        default:
            cout<<"Wrong Choice"<<endl;
        }
    }
    return 0;
}

node *stack_list::push(node *top, int item)
{
    node *tmp;
    tmp = new (struct node);
    tmp->info = item;
    tmp->link = top;
    top = tmp;
    return top;
}

node *stack_list::pop(node *top)
{
    node *tmp;
    if (top == NULL)
        cout<<"Stack is Empty"<<endl;
    else
    {      
        tmp = top;
        cout<<"Element Popped: "<<tmp->info<<endl;
        top = top->link;
        free(tmp);
    }
    return top;
}

void stack_list::traverse(node *top)
{      
    node *ptr;
    ptr = top;
    if (top == NULL)
        cout<<"Stack is empty"<<endl;
    else
    {
        cout<<"Stack elements :"<<endl;
        while (ptr != NULL)
        {
            cout<<ptr->info<<endl;
            ptr = ptr->link;
        }
    }
}