Space reclamation processes

[ProtoTipo srl]

Hi all,
we have a library with four DLT drives. During the expire inventory,
several space reclamation processes start, using all drives in the library.
I'd like to keep two drives free for migration.
Is there a way of limiting the number of drives used by space reclamation?
I know there's a device class MOUNTLIMIT parameter, but it affects also
other processes such as migration...

Thanks in advance,
               Stefano