This simple design, possible because the data obeys strict LIFO order, means that no complex data structure is needed to track stack contents - a simple pointer to the topof the stack will do.
If a function is executing, then the stackpointer is pointing to the topof the whole stack, which is also the top of that function's activation record.
如果一个函数正在执行,那么堆栈指针就会指向整个堆栈的顶部,这也是该函数活动记录的顶部。
3
As we click around in the application, new events will be pushed onto the topof the stack, and the pointer will identify the last element added.