You can change log levels by modifying log4j.logger.loggerName properties in <install path>\CAS\workspace\conf\cas-service-log4j.properties. The default log level is set to WARN.

For example, this Log4J entry sets the log level to DEBUG for the sample substring manipulator.

log4j.logger.com.endeca.cas.extension.sample.manipulator.substring.SubstringManipulatorRuntime=DEBUG

After you modify, save, and close the cas-service-log4j.properties file, you must restart the CAS Service for the change to take effect.