Not according to the comment that I am replying to:

> A reference is basically a pointer that the language prevents you from doing pointer arithmetic on, and in many languages such as PHP, is simply automatically dereferenced for you.

Also, the implicit is usually pass-by-value.

    function foo(a) { a++; }
    function bar(ref a) { a++; }
    b = 1;
    foo(b); // Pass by value, implicit.
    assert(b == 1);
    bar(ref b); // Pass by reference.
    assert(b == 2);

Heap vs. stack values are not the same thing as pass-by-reference and pass-by-value.