The runtime data structure that is used to manage the execution of methods:

When a Java program starts running, a main method is typically invoked. When the main

method calls another method, the Java Virtual Machine $($JVM$)$ xreates a new activation

record and pushes it onto the top of the activation stack. This activation record, also known

as a stack frame, contains information about the method being called, including the

method's local variables and its return address.

If the called method in turn calls another method, another activation record is created and

pushed onto the top of the stack, with its own set of local variables and return address. This

process continues until all the methods have completed their execution and returned their

values.

When a method completes its execution, its activation record is popped off the stack, and

the control returns to the calling method. The calling method then continues its execution

from the point where it made the method call.

The activation stack plays a crucial role in the proper execution of Java programs, as it

ensures that methods are executed in the correct order and that each method has access to

its own set of local variables. It also allows for the proper handling of exceptions and the

propagation of values returned from called methods to the calling methods.

Critical Thinking Questions

Summarize their key common characteristics in a few complete English sentences.