The TP message log can be used for recovery and problem determination when an error occurs while a TP is processing. You can control the TP message log through parameters from the TP profile and from the APPC/MVS transaction scheduler parmlib member (ASCHPMxx). Some parameters control how much I/O is required to write messages to the log, and how much storage APPC/MVS uses. Once a TP is in production, you might want to alter the parameter values to limit the use of logs. For a description of the parameters and possible values, see Logging Transaction Program Processing.