Are references stored on the heap or stack?

Question

I wonder whether the reference variables such as c in this code:

int a = 5;
int & c = a;

are allocated from heap or stack.

Answer 1

A reference is just an alias, and it is unspecified by the C++11 Standard whether it requires actual storage or not.

Per Paragraph 8.3.2/4 of the C++11 Standard:

It is unspecified whether or not a reference requires storage (3.7).