When you have finished performing the activity to be traced, turn off the VTAM TYPE=BUF trace for the Mainframe Access ACB. Use the z/OS Modify command as follows:
F VTAM,NOTRACE,TYPE=BUF,ID=MFM62ACB
IST097I MODIFY ACCEPTED
IST1143I TRACE TERMINATED FOR DDINET1.MFM62ACB 349
IST1045I NODE TYPE = APPL
IST314I END