Keeps track of recursive {@link Invocation}s. This stack assumes an invocation occurs in the same thread since it is called first, so we manages stacks for each invocation in {@link ThreadLocal}-like manner. You can just use {@link #getInstance()} to get current invocation stack.
@author
Apache Directory Project
@version $Rev: 896599 $, $Date: 2010-01-06 19:26:43 +0100 (Mer, 06 jan 2010) $