STACK AND HEAP

I felt that these two terms are used a lot while discussing linux so a quick look at these two topics would be good.

The stacks and heaps are the part of virtual address space that consists of code;data;heap(growing upwards) and stack portion(growing downwards).( from bottom to top).

STACK:

• This is the memory area used by our thread of execution.
• When a function is called the local variables and return addresses are stored here.
• The space becomes available when the function  exits.
• The user doesn't need to take care of the memory allocation and deallocation( happens automatically).

HEAP:

• It is the memory set aside for dynamic allocation.
• Generally, an application is given a separate heap memory and it allocates the memory from the given heap on need basis.
• WE can allocate and free heap anytime.
• User must take care of deallocation of memory when he doesn't need it.
• To get heap memory we use malloc and calloc if we are in user space and if we are in kernel space we use kmalloc, vmalloc.
• We must free the memory allocated by using free, kfree and vfree respectively.