The NPF system also has a tracing facility to track the NPF internal processing that occurs during interactive ISPF sessions. The tracing facility can be turned on and off from the interface. It is normally used only for short periods of time when diagnosing problems and collecting information to forward to IBM® service representatives.

Your system can have as many trace files as needed. The trace file that is used during an ISPF session is specified on the NPF Diagnosis Functions Panel. If a user specifies a data set that does not exist and the data set name begins with the user's TSO user ID, the system will dynamically allocate the file. All other trace files (those with a high-level qualifier other than the user ID) must be allocated with the following specifications: sequential organization (PS), a variable block format (VB), a logical record length (LRECL) of 132, and any block size (BLKSIZE).