Environnement : WAS v5.1 on z/OS (1 region controller + 2 servants)

I'm trying to implement a Object cache using the com.ibm.websphere.cache.DistributedMap which is part of the dynamic cache library in WAS. This object can be looked up using JNDI, the problem is that i don't know if this object resides in the controller or the servant JVM (i don't want to have an instance of this object per servant).
Could you tell me if the JNDI context is stored in the region controller or in each servant?