调用栈（call stack）

调用栈的英文叫做call stack，从其英文书名来看，知道它本身就是一个栈，故而它满足栈的先入后出的特性。

wiki上有篇文章讲述call stack：http://en.wikipedia.org/wiki/Call_stack

关于栈的溢出(stack overflow)，有下面的定义：

Since the call stack is organized as a stack, the caller pushes the return address onto the stack, and the called subroutine, when it finishes, pops the return address off the call stack and transfers control to that address. If a called subroutine calls on to yet another subroutine, it will push another return address onto the call stack, and so on, with the information stacking up and unstacking as the program dictates. If the pushing consumes all of the space allocated for the call stack, an error called a stack overflow occurs, generally causing the program to crash.

关于call stack的作用，它也谈到了：

Storing the return address When a subroutine is called, the location (address) of the instruction at which it can later resume needs to be saved somewhere. Using a stack to save the return address has important advantages over alternatives. One is that each task has its own stack, and thus the subroutine can be reentrant, that is, can be active simultaneously for different tasks doing different things. Another benefit is that recursion is automatically supported. When a function calls itself recursively, a return address needs to be stored for each activation of the function so that it can later be used to return from the function activation. This capability is automatic with a stack.

存储指令的返回地址，是call stack最重要的作用，简单，而且会带来很多其它的好处，譬如每个线程维护自己的调用栈，还有递归调用。

Local data storage A subroutine frequently needs memory space for storing the values of