Double stack linked list segmentation fault

Question

So I've been asked to make a C++ program Double stack with linked list. I can't find any tutorial or example on Google, most of them use Array to do it. so I have to figure it out how to do this, and end up with Segmentation Fault output in the end, which I still have no idea which part of my code is wrong here

#include <iostream>
using namespace std;

struct Node{
    public:
    int data;
    Node *next;
    Node *prev;
};
Node *head = NULL;
Node *tail = NULL;
Node *del = NULL;

void push(Node **head_ref, int data){
    Node *temp = new Node;
    temp->data = data;
    temp->next = head;
    head->prev = temp;
    head = temp;
}

void push2(Node **head_ref, int data){
    Node *temp = new Node;
    temp->data = data;
    tail->next = temp;
    temp->prev = tail;
    tail = temp;
}

void pop(Node **head_ref, int data){
    del = head;
    head->next->prev = NULL;
    head = del->next;
    del = NULL;
}

void pop2(Node **head_ref, int data){
    del = tail;
    tail->prev->next = NULL;
    tail = del->prev;
    del = NULL;
}

int peek(Node **head_ref){
    return head->data;
}

int main(){
    system("clear");
    push2(&head, 10);
}

any help is appreciated