The preallocationStrategy for KahaDB is not documented in section 2.2. CONFIGURING THE KAHADB MESSAGE STORE [1].

This feature was introduced with:

https://issues.jboss.org/browse/ENTMQ-512

The preallocationStrategy is documented at Apache [2]

[1] https://access.redhat.com/documentation/en-US/Red_Hat_JBoss_A-MQ/6.2/html/Configuring_Broker_Persistence/KahaDBConfiguration.html

[2] http://activemq.apache.org/kahadb.html