Stack Vs Heap

Stack vs heap are the two terms that every beginner of the programming languages gets to know and hear. Without any detailed explanation, stack vs heap is often heard in the field of programming language. It is beneficial to seek information related to stack and heap memory in order to understand and function well.

What is a Stack?

To know more detailed differences between the heap and stack, it is crucial to know the details of both respectively. Variables are declared in the stack and are stored during the time of operation. The stack is considered as the temporary memory of your computer.

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When the functions or the tasks of your computer are done, then the memory of the variants is erased instantly. This process is automated. All variables will be erased after the completion of the tasks.

What is Heap?

The heap is also a memory that is mainly used by the programming languages to store global variables. All global variables are placed in the heap memory. Heap is not managed by the CPU, and more likely, it works as a free-floating region of the memory.

Basic differences between Stack vs Heap:

To talk about the basic differences between them, it is quite essential to learn things related to stack and heap memory. There are several differences between stack vs heap in JavaJava.

  • The major difference between stack and heap is that the use of stack memory is in local store variables and mainly operates calls. On the other hand, heap memory is widely used to store the objects in JavaJava. Heap memory stores every Dara and doesn’t matter where the object is created in code. Member variables, class variables, or local variables, all are stored inside the heap space in JavaJava.
  • Users can specify the size of the heap of the java program with the help of using the JVM option, and the size of the heap is considered as the maximum size of the java heap. At the same time, stacks are used to specify with the help of using the JVM parameter.
  • The size of the memory capacity of the stack is less than the heap memory in JavaJava.
  • The variable which is stored in stacks memory is visible to the owner threads only, but the objects which are placed inside the heap memory are visible to all threads.
  • Stack memory is more secured as compared to heap memory.
  • The stack is a linear structure of data. On the other side, the heap is a hierarchical structure of data.
  • It has the ability to become fragmented, while the heap memory can become fragmented.
  • Stack memory access local variables only, but the heap memory allows users to access variables globally.
  • The biggest difference between stack vs heap is that stack memory is mainly allocated in contiguous blocks, while on the other side; heap memory is allocated in any random pattern.
  • Stack variables are not able to get resized, whereas the heap variables can be easily resized.
  • If we talk about the access speed, then the stack provides a high speed of access as compared to the heap access speed. Mainly stack has high-speed access while heap has slower access speed.
  • The allocation and deallocation of stack memory are done automatically by the compiler instructions. On the other side, the allocation and deallocation of the heap memory are done by the programmer.
  • The deallocation of the stack does not require deallocating the variables, whereas the deallocation of the heap memory needs explicit deallocation.


Both stack vs heap memory is beneficial in other ways. Basically, both are a part of memory and are allocated and mainly used for other purposes. Java programs run on JVM, and many use stack and heap memory for specific requirements.

The stack is known as the specific area of the memory of computers which mainly allows storing temporary variables that are created by a function. Heap memory supports dynamic memory allocation. The heap memory system is not handled automatically like stack memory.