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374 VM/HSC 6.0 System Programmer’s Guide
1st ed., 6/30/04 - 312579601
HSC Internal Trace Table
The HSC itself has an internal trace table. It is pointed to by the contents of the 4-byte
field at offset x’40’ from the start of the LVT (LVTTBLK).
It is a wrap-around table, recording the last 256 events that occurred in the HSC
subsystem. There are more than 90 different types of events. Trace entries are 108 bytes
long. The data traced will be truncated in order to fit into the table entry.
Programs issue an SLSTRACE macro at important trace points. The routine that is called
by the macro checks to see if tracing of the caller’s software component has been enabled.
The internal trace table is always updated. If the caller’s component has been enabled (by
the HSC ‘TRACE’ command), then GTRACE will also be invoked to produce an external
trace record for later analysis.
Table 22. Format of HSC Internal Trace Table
Offset Length Description
Header - 16 bytes long:
+0 4 Identifier - ‘BTRC’
+4 4 Length of trace table
+8 1 Subpool number
+9 1 Protection key
+A 6 Reserved for future use
ENTRIES - 108 bytes long:
+0 2 Trace identifier
+2 5 Name of module cutting the record
+7 1 *Length of data area used
+8 2 Trace module offset
+A 1 *Flag bits
+B 1 *Sequence number of this record
+C 4 Trace TBLOK address
+10 4 Reserved
+14 88 Trace data from component
Note: These fields (*) do not apply to internal trace records.