The Trace File

You can view or print the GTF trace file using any ASCII-compatible editor or word processor. The file begins with the GTF options used to generate the file and the date and time the trace started. The last line of the file shows the date and time the trace ended. If this line is not present, the trace is probably incomplete because it was not closed properly. This can happen if you are running an interactive debugging session using the Assembler debugger with the Generalized Trace Facility turned on, and an unrecoverable error occurs. To ensure that the GTF trace file is complete, you must allow the debugging session to end without being forced: press S(tep) or G(o) to record the program exception on the trace file and then stop the debugging session.

In between the information at the beginning of the file and the last line are individual trace records. Each of these includes the following items of information:

• Instruction count. This is a hexadecimal counter showing the total number of instructions executed up to the trace point. This count is very useful when you want to work out where to start a detailed trace at a point deep into a complex application where the same code may be executed many times before the point of failure. You use the option GTFIMIN to set the starting instruction count for a trace.
• Instruction address. This is the linear address of the next instruction at the current trace point. This address provides an alternative way of specifying where you want a detailed trace to start. You use the option GTFAMIN to set the starting instruction address for a trace.
• Instruction operation. This field indicates the machine instruction or run-time operation being performed at the trace point. Additional information may follow depending on the type of trace line: INS The hexadecimal machine instruction, which can be 2, 4, or 6 bytes in length

PGM

The program name and entry for LOAD, DELETE, or LINK

FOC and FIO

The DCB, ACB, or DTF control block address

MEM

Length and address of memory allocated or deallocated