Stack vs Heap Memory Allocation Data Structure

Difference Between Stack and Heap Memory Allocation

Stack Memory

Stack memory allocation is a way to use the system memory as a temporary storage of the data which is act like last-in-first-out buffer. When the allocation of the memory happens on contiguous blocks called it stack memory allocation or we can say a stack memory is a special place of system memory which is able to store temporary variables created by a function. During the run time of an application, the stack memory is used to declare the variable, store and initialized the variable and when the task of an application is done then the memory of the variables will be automatically erased. The stack memory contains local variables, methods and reference variables. The programmer doesn’t need to care about memory allocation and de-allocation because all things happen by some predefined routines in the complier.

Heap Memory

The heap memory is the memory which is used to store global variables by the programming languages. Every time when we make an object so these objects are created in heap memory and the address information of these objects are stored in stack-memory. The heap space is not managed automatically it is managed by the programmer itself because it’s a kind of free-floating region of the memory. The heap memory allocation is not safe as compared to stack memory allocation because the data stored in heap memory is accessible or visible to all threads. If a programmer doesn’t manage this memory well then, a memory leak can happen in the program.

Key Differences

• The stack memory is a linear data structure and the heap memory is hierarchical data structure.
• The heap memory in an application exists as long as the application runs whereas the stack memory is de-allocated when the task is done.
• The stack memory accesses the local variables only and the heap memory accesses the global variable.
• The stack memory is allocated in a contiguous block and the heap memory is allocated in any random order.
• In stack memory, the allocation and de-allocation are managed by compiler and if we talk about the heap memory then it will take care by the programmer itself.
• The stack memory is faster as compared to heap memory because it is allocated in contiguous memory blocks.
• The size of stack memory is quite lesser than the heap memory.
• The stack memory is much safer as compared to heap memory because it stores local methods and variables whereas the heap memory is visible to all threads.

Comparison Table: -

Parameter		STACK		HEAP
Basic		Memory is allocated in a contiguous block.		Memory is allocated in any random order.
Allocation and De-allocation		The allocation and de-allocation are done by compiler automatically.		In heap memory, it is done by programmer manually.
Cost of memory		Less		More
Implementation		The stack is difficult to implement.		The heap memory is easier to implement.
Access time		The access time of stack memory is faster than the heap memory		Slower
Main Issue		Shortage of memory		Memory fragmentation
Flexibility of the memory		We can’t resize of it.		Resizing is possible
Data type structure		Linear data structure		Hierarchical data structure