Dynamic stack implementation in C

stack.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#define stype unsigned long long

struct list {
        struct list *prev;
        stype val;
};

typedef struct stackStruct {
        int size;
        struct list* ptr;
} stack;

stack *newStack()
{
        stack *s = malloc(sizeof(stack));
        s->size = 0;
        s->ptr = malloc(sizeof(struct list));
        s->ptr->prev = NULL;
        return s;
}

void stackPush(stack *s, stype value)
{
        s->ptr->val = value;
        void* ptr = s->ptr;
        s->ptr = malloc(sizeof(struct list));
        s->ptr->prev = ptr;
        ++s->size;
}

stype stackPop(stack *s)
{
        if(!s->size)
        {
                puts("No items in the stack");
                abort();
        }
        stype val = s->ptr->prev->val;
        void* ptr = s->ptr->prev;
        s->ptr->prev = s->ptr->prev->prev;
        free(ptr);
        --s->size;
        return val;
}

bool stackEmpty(stack *s)
{
        return !s->size;
}

stype stackPeep(stack *s)
{
        return s->ptr->prev->val;
}