版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/carlhelen/article/details/89027696
The stack is a data structure that expands and contracts in response to procedure invocations and returns, among other things.
At runtime, the system places all automatic variables (nonstatic local variables), subroutine parameters, temporary values, and other objects in the stack section of memory in a special data structure called the activation record (the activation record is aptly named because the system creates an activation record when a subroutine first begins execution and deallocates the activation record when the subroutine returns to its caller).