TRACE To resume operation of the virtual machine, the BEGIN command must
be entered. If the RUN operand is specified, the virtual machine is
not.stopped after each output message.
4. If trace output is beinq recorded on a virtual spooled printer, a CLOSE command must be issued to that printer output to be printed on the real printer.
., ... • u 5. Successful branches to the next sequential instruction and
branch-to-self instructions are not-detected by TRACE.
6. RUN and RORUN can be specified in different TRACE commands with no
conflict as lonq as the functions being traced are different.
7. Instructions that modify or examine the first two bytes of the next
sequential instruction cause erroneous processing for BR&NCH and INSTRUCT tracinq.
8. When tracing on a virtual machine with only one printer, the trace
data is intermixed with other data sent to the virtual printer. To
separate trace information from other data, define another printer
with a lower virtual address than the previously defined printer. For example, on a system with OOE defined as the only printer,
define a second printer as OOB. The regular output goes to OOE and
the trace output goes to OOB. 9. If the BRANCH, INSTRUCT, or ALL activities are being traced by a virtual machine using a shared system, the user receives a warning
message and the virtual machine is unshared from (given a private
copy of) the named system. Other users of the segment continue to
operate with an unchanged copy of that segment. 10. 110 for virtual channel-to-channel adapters, with both
ends connected to the same virtual machine, cannot be traced. 11. Use the TRACE command to trace specified virtual machine activity
and to record the results at the terminal, at a virtual printer, or
at both. This command is useful in debugging programs because it allows you to trace only the information that pertains to a
particular problem.
12. If your virtual machine is doing I/O that results in
program-controlled interruptions (PCls), and you are tracing I/O or CSW activity, some of the PCls may not be traced. This situation
arises when the system is extending its free storage area and the
additional demand on available free storage could cause a system
abend.
13. The PA1 key on a 3270 display terminal shOUld not be pressed with trace all run active while the display screen indicates status as a subsequent CP command entered from the console may result in interleaved output.
section 5. Format of CP Commands 163

TRACE The symbols are used in the responses received from TRACE: vvvvvv tttttt
rrrrrr
xxxxxxxx yyyyyyyy ss ns zz
zzzzzzzz
type
V vajd R rajd mnem
int
code
CC n
IDAL
***
==> SEEK TRACE STARTED !1gg!li!lg virtual storage address
virtual transfer address or new PSW address
real storage address
virtual instruction, channel command word, :SW status
real instruction, CCW arqument byte (SSM-byte) for SSM instruction
new system mask after execution of STJSM/STNSM low order byte of R1 register in an execute instruction
(not shown if R1 register is reqister 0) referenced data
virtual device name (DASD, TAPE, LINE, CONS, RDR, PFT, PUN, GRAF, DEV)
virtual device address
real device address
mnemonic for instruction
interruption type (SVC, PROG, EXT, I/O)
interruption code number (in hexadecimal)
condition-code number (0, 1, 2, or 3)
Indirect data address list
virtual machine interrupt
privileged operations
transfer of control
read/write position on DASD device
This response is issued when tracing is initiated. TRACE ENDED
This response is issued when tracing is suspended. riO vvvvvv TCP xxxxxxxx type vadd CC n I/O vvvvvv mnem xxxxxxxx type vadd CC n t1pe radd CSW xxxx liD vvvvvv mnem xxxxxxxx type vadd CC n type radd CSW xxxx CAW vvvvvvvv CCW vvvvvv xxxxxxxx xxxxxxxx rrrrrr YYYYY11Y Y1YYYYY1 CCW IDAL vvvvvvvv vvvvvvvv IDAL OOrrrrrr OOrrrrrr CCW SEEK xxxxxxxx xxxxxx SEEK 1Y1YYYY1 11YY The IDAL SEEK line is included only if applicable. The virtual IDAL
is not printed if the real CCW operation code does not match the real
CCW.
164 IBM CP Command Reference for General Users