Final answer:
The statement that a subroutine's stack frame always contains the caller's return address and the subroutine's local variables is true.
Step-by-step explanation:
A subroutine's stack frame indeed always includes the return address for the caller and the subroutine's local variables, allowing for proper control flow and variable scope.
In computer programming, especially in the context of assembly language or low-level languages such as C, a stack frame is a section of the computer's stack memory that contains these elements. The return address is used to control the flow of the program once the subroutine has finished executing, guiding the program counter back to the appropriate line of the calling function. The local variables are stored in the stack frame to provide the subroutine with its scope of work, isolating these variables from the rest of the program.
Example of a Stack Frame
For instance, when a function is called in C, a stack frame is created to hold the function's parameters, return address, saved registers, and local variables. This stack frame is then popped off the stack when the function returns.