Hi Martin, and all folks that already answered my question ...

First of all, thanks a lot for everyone that sent me an answer, most of
the time not the one I expected, but never mind ;-)

Martin, you're absolutely right, but in my case the problem was not to
avoid reclamation occuring, but to stop it once it's started (impossible
on a copy stg pool, without a cancel command). Thanks anyway !
Regards.
Arnaud