MAKE_STD_ZVAL and pointer address

Hi! I have quite simple function which returns zval and in some cases it's invoked in a loop. There is a problem with returned variable at PHP level. However it's very random. The C function is almost like this: zval *_ret; MAKE_STD_ZVAL(_ret); some_function_which_sets_zval_type(_ret); RETURN_ZVAL(_ret, 1, 1); I added a debug statement (after MAKE_STD_ZVAL), which prints pointer address (%p). When this function is executed on PHP level in a loop, _ret address is always the same. Even if there are hundreds steps in a loop. Is it normal? I see new pointer is allocated (at new address) when I call zval_add_ref(&_ret); But I am not sure what is general purpose of zval_add_ref. Any suggestion? Piotras