GTF creates a control record at the start of each block of trace
output. The control record can be followed by lost data, user data,
and system data records. If this trace output was merged from multiple
systems using the IPCS COPYTRC subcommand, then the control record
reflects the combined GTF options in effect from all the systems.
See z/OS MVS IPCS Commands
for more information about the COPYTRC subcommand. Figure 1 shows the format of a control record.
Figure 1. Unformatted control
record┌──────┬─────┬─────┬─────┬─────────┬──────────┬───────┐
│length│ res │ AID │ FID │time zone│time stamp│options│ ... source descriptors ...
└──┬───┴──┬──┴──┬──┴──┬──┴────┬────┴────┬─────┴───┬───┘
2 2 1 1 4 8 8
bytes bytes byte byte bytes bytes bytes
The fields in the control record contain the following information:
- length
- Total length of the record, in bytes.
- res
- Two bytes of zeroes. Reserved for IBM® use.
- AID
- Application identifier, which is always zero for control records.
- FID
- Format identifier of the routine that will format the record,
which is always X'01' for a control record.
- time zone
- Value showing the difference between local time and Greenwich
mean time (GMT) in binary units of 1.048576 seconds when tracing began.
- time stamp
- Time stamp showing the eight-byte Greenwich mean time (GMT) when
the control record was created.
- options
- An eight-byte field containing the following: The first five bytes
identify the GTF options in effect for a block of trace output. See
mapping macro AHLZGTO in z/OS® MVS™ Data Areas in z/OS Internet library.
The remaining
3 bytes contain the following important flags, in bit ranges 0-7:
- GTWCFSID - Byte 6, Bit 6
- 1, if the individual trace records have SIDs (system identifiers)
indicating that the GTF trace data from multiple systems was merged
using the IPCS COPYTRC command. In this case, there is multiple source
descriptors, one for each system. The source descriptors are ranged
in order by system identifier (SID). Use the value in the SID field
as an array index to locate the source descriptor for a particular
system.
The source descriptor information is identical in all control
records within a single trace data set.
0, if the trace records
have no SIDs.
- GTWCFNEW - Byte 6, Bit 7
- 1.
- Source descriptors
- One or more arrays of information about the origins of the records
in this block of trace data, such as the release level of the system
issuing the trace data and the GTF options in effect. If GTF trace
data was merged from multiple systems, there are multiple source descriptors,
one for each system. Use the value in the SID field as an array index
to locate the source descriptor for a particular system.
See mapping
macro AHLZGTS in z/OS MVS Data Areas in z/OS Internet library, and check
the format of the source descriptor information.