Is RCS MT_Safe?

Hi,

I am trying to use rcs library in a native code for a Java App server 
using JNI.
The native manager that calls the native methods is multi-threaded, and 
having more than 1 thread crashes the JVM, with wierd RCS errors which 
look like memory corruption.

So my question would be, is there a Thread-safe version of the RCS library?

Thanks,
Ravi