Stack vs Heap Memory

• Stack is a linear data structure whereas Heap is a hierarchical data structure.
• Stack memory will never become fragmented whereas Heap memory can become fragmented as blocks of memory are first allocated and then freed.
• Stack accesses local variables only while Heap allows you to access variables globally.
• Stack variables can’t be resized whereas Heap variables can be resized.
• Stack memory is allocated in a contiguous block whereas Heap memory is allocated in any random order.
• Stack doesn’t require to de-allocate variables whereas in Heap de-allocation is needed.
• Stack allocation and deallocation are done by compiler instructions whereas Heap allocation and deallocation is done by the programmer.What is a Stack?A stack is a special area of computer’s memory which stores temporary variables created by a function. In stack, variables are declared, stored and initialized during runtime.It is a temporary storage memory. When the computing task is complete, the memory of the variable will be automatically erased. The stack section mostly contains methods, local variable, and reference variables.What is Heap?The heap is a memory used by programming languages to store global variables. By default, all global variable are stored in heap memory space. It supports Dynamic memory allocation.The heap is not managed automatically for you and is not as tightly managed by the CPU. It is more like a free-floating region of memory. 

Advantages of using Stack

• Helps you to manage the data in a Last In First Out(LIFO) method which is not possible with Linked list and array.
• When a function is called the local variables are stored in a stack, and it is automatically destroyed once returned.
• A stack is used when a variable is not used outside that function.
• It allows you to control how memory is allocated and deallocated.
• Stack automatically cleans up the object.
• Not easily corrupted
• Variables cannot be resized.

Advantages of using Heap

• Heap helps you to find the greatest and minimum number
• Garbage collection runs on the heap memory to free the memory used by the object.
• Heap method also used in the Priority Queue.
• It allows you to access variables globally.
• Heap doesn’t have any limit on memory size.

Disadvantages of using Stack

• Stack memory is very limited.
• Creating too many objects on the stack can increase the risk of stack overflow.
• Random access is not possible.
• Variable storage will be overwritten, which sometimes leads to undefined behavior of the function or program.
• The stack will fall outside of the memory area, which might lead to an abnormal termination.

Disadvantages of using Heap

• It can provide the maximum memory an OS can provide
• It takes more time to compute.
• Memory management is more complicated in heap memory as it is used globally.
• It takes too much time in execution compared to the stack.

When to use the Heap or stack?

You should use heap when you require to allocate a large block of memory. For example, you want to create a large size array or big structure to keep that variable around a long time then you should allocate it on the heap.

However, If you are working with relatively small variables that are only required until the function using them is alive. Then you need to use the stack, which is faster and easier.