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372 VM/HSC 6.0 System Programmer’s Guide
1st ed., 6/30/04 - 312579601
SCP GTRACE Emulation
The SCP emulates the following MVS GTRACE features:
1. The MVS GTRACE macro is supported, without alteration.
2. A Monitor Call (MC) program interrupt occurs when the GTRACE function is
invoked. The SCP program check handler recognizes and handles the Monitor Call
as a GTRACE event.
3. Up to 256 bytes of user data may be traced.
4. With most interrupts, the SCP dispatcher does not return to the interrupted task
immediately, but dispatches the next task in the priority queue. However, after a
monitor call program interrupt the interrupted task IS returned to immediately. If this
were not done, program flow would be artificially altered by the act of tracing.
5. The Format Id (FID) parameter is supported. It describes the internal format of the
trace record. The valid (decimal) FID ranges are:
1 <= user FID <= 80
81 <= system FID <= 255
Actual FIDs used by the SCP are:
The actual FID used by the HSC is passed to the HSC initialization routine
(SLSBINIT), and is recorded in the ACS SYSPROF file. The default FID is 23.
6. The Event ID (EID) parameter is supported. It describes the event as a subtype of the
Format ID.
It is specified as a 4-digit hexadecimal number, of which the left-most digit is the
monitor call class.
Table 21. FIDs Used by SCP
Decimal Hex Char Meaning
195 x’C3’ c’C’ IUCV event
196 x’C4’ c’D’ Dispatcher event
197 x’C5’ c’E’ External interrupt
201 x’C9’ c’T’ I/O interrupt
212 x’D4’ c’M’ Machine check interrupt
215 x’D7’ c’P’ Program interrupt
217 x’D9’ c’R’ Restart interrupt
226 x’E2’ c’S’ Start I/O
229 x’E5’ c’V’ Supervicor call interrupt
230 x’E6’ c’W’ Return from SVC