The Java Transformer started task is generating thousands of messages in the D2ETRACE DD even with the D2E_TRACE parameter commented out in the STDENV file:
Release : 12.0
Component : CA Spool
The trace was being created by the option V in the TRANSFRM keyword.
"V - Adds trace entries related to the AFP to PCL Soft Font processing to the D2ETRACE sysout file. V can be used without specifying any D2E_TRACE environment variable."
Removing this option solved this problem.