At initialization, the master scheduler sets up a master trace table of 24 kilobytes. A 24-kilobyte table holds about 336 messages, assuming an average length of 40 characters. You can change the size of the master trace table or specify that no trace table be used by changing the parameters in the SCHEDxx parmlib member.
TRACE MT,36K
See z/OS MVS Initialization and Tuning Reference for more information about the SCHEDxx member.