program to find the largest element in stack while implementing linked list but the data is not being accesed

  #include<stdio.h>
    #include<stdlib.h>
//structure//
    struct node
    {
    int data;
    struct node *link;
    };
//function to push elements into stack//
    void push(struct node *top_ref,int x)
    {
    struct node *new=(struct node *)malloc(sizeof(struct node));
    new->data=x;
    new->link=top_ref;
    top_ref=new;
    }
//function to get largest element//
    int largest(struct node *top_ref)
    {
    int temp=0;
    while(top_ref!=NULL)
    {
    if(temp<top_ref->data)
    {
    temp=top_ref->data; 
    }
    top_ref=top_ref->link;
    }
    return temp;
    }
//function to print the stack//
    void print(struct node *top_ref)
    {
    while(top_ref!=NULL)
    {
    printf("%d->",top_ref->data);
    top_ref=top_ref->link;
    }
    printf("\n");
    }
//main function//
    int main()
    {
    struct node *stack=(struct node *)malloc(sizeof(struct node));
    stack=NULL;
    push(stack,1);
    push(stack,5);
    push(stack,6);
    push(stack,3);
    print(stack);
    printf("the largest no. is %d\n",largest(stack));
    }

trying to find the largest no. in a stack there is a problem in line 20 ,32 top_ref->data is not being accesed top_ref is the last node of the linked list new to linked list and data structures

the output i am getting is

empty line 
the largest no. is 0