I believe they had similiar aircraft storage units and depots like the Allies, plus subcontractors in France and Holland doing some major repair work, at least in the West.
This is a topic that have many interesting bits of info laying scattered around everywhere, but I am not sure I've seen any good source compiling the whole issue and presenting it in a uniform manner...
Any good titles or sources on LW repair organisation and aircraft distribution, how it worked? Erich?