Do different programs gets their memory from a common heap or from a separate heap?

Question

I am a bit confused how glibc on linux allocates its memory to various program.These are the few questions:

1. Is it been allocated from a common heap(i.e is there

Answer 1

Each process has its own virtual heap. It may, however, share physical RAM, or not, depending on access. See copy-on-write for some more background.