Stack frame definition
A stack frame, often just called a ‘frame,’ is a section of the stack dedicated to a particular function call. The stack is a region of memory that supports push and pop operations and is used to store data in a Last-In-First-Out (LIFO) manner.
How stack frames work
When a function is called, a new stack frame is pushed onto the call stack. This frame contains data specific to that function, including its local variables, return address, and sometimes arguments passed to the function. As the function executes, its frame provides the necessary context. When the function completes, its stack frame is popped off the stack, and control returns to the calling function.
Each frame usually stores:
- Local variables. These variables are local to the current function. They get created and live within the stack frame for that function call.
- Return address. When a function completes its execution, the program needs to know where to continue. The return address tells the program where to jump back to in the calling function.
- Saved registers. These are the values of any CPU registers that need to be restored when the function returns, ensuring that the function doesn’t unintentionally alter the state of the system.
- Parameters. The values that are passed into the function.
- Control data. It includes information about the state of the calling function and other necessary metadata.
- Base pointer (or frame pointer). It’s used to access parameters and local variables in a consistent way, especially in the presence of dynamic memory allocations within the stack frame.