How to prevent 'Unchecked_Access

[geert@fozzie.sun3.iaf.nl (Geert Bosch)]

OK, as long as there is no GC for GNAT I'd like to use the stack
whereever I can to prevent errors in memory management. Sadly
enough there are many times I need to pass access types to procedures
at library level, notably OS and GUI libraries. 

Although I understand the use of Ada-95 accessibility levels to
prevent dangling pointers (dangling access objects???), there are
many times Unchecked_Access is necessary to pass parameters to
a subprogram that is known not to secretly store it somewhere for
later reuse.

Isn't there a way to express this safe behavior at the subprogram, so
they can be used without using Unchecked_Access. A pragma specifying
that an access-type parameter is limited would seem logical.

For those who might think that this question falls into the
category "how do I turn this screw without using the screwdriver",
I'd like to point out that the situation I describe doesn't
have to be "Unchecked".

Subprograms that take these limited access types as parameters can be
checked at compile time so there is nothing Unchecked taking place.
Reserving a dangerous feature for places which *are* potentially
dangerous is better IMHO that using it all over the place.

Of course specifying the pragma for imported C functions is
potentially unsafe, but importing C functions was unsafe 
already.

I'm very interested in your opinions on this.
-- 
E-Mail: geert@sun3.iaf.nl