Answer 1

What would you do when you don't know the maximum amount of memory your program would be allocating ?

Answer 2

Scope is also one consideration, heap based memory lifetime is not limited as is the stack based memory. Memory allocated on the heap stays until explicitly destroyed, with the exception of smart pointers, *probably* ...

https://stackoverflow.com/questions/40701228/why-do-we-use-heap-to-store-memory

Answer 3

Not only two memory area stack, heap are available read about assembly you will understood better about memory concepts and working process.