Table of Contents

Heap vs Stack

Whenever a class is executed by specifying its corresponding class name using the command “java {classname}” the java launcher JAVA immediately initiates the Java run-time environment for the class execution as a layer on top of the operating system.

Java Heap

Main memory of JVM.
Objects of classes.
Non-static variables memory is created.
Method area and heap area both are memory sharable areas.

Java Stack

All java methods are executed.
JVM by defaults creates Main Thread and Garbage collector thread
Each method execution JVM creates a separate block in the main thread. This is called the Stack Frame.
Java operations are called Stack Frame operations because every method is executed only in the stack.

Stack Frame is a sub-block inside a thread created to execute a method or block and is destroyed automatically after the completion of the method. If the method has any local variable they all are created inside the method’s stack frame and are destroyed automatically when the stackframe is destroyed. Stack Frame is divided into 3 blocks:

Variables storage area:for method’s local variable
Instruction storage area: To store instruction information
Method stack:To execute method.

—