Exit EXECs
Exit EXEC Interface I Communication Error Exit I LOG Error Exit
The programmable operator facility exit EXECs have the same parameter list pro­
vided as an EXEC action routine, with the exception that no RT ABLE parameter
field value and no message text are stacked for the EXEC. When an exit EXEC is
called, contents of the program stack depend upon which exit is being invoked.
Descriptions of the stack contents for the different types of exits follow:
Notes:
1. Some of the parameter values have no meaning for a particular exit EXEC and
their use is left to the discretion of the EXEC writer. For example, requester's
userid and nodeid have no meaning for the communication error EXECs, PROPPCHK and PROPHCHK. 2. The programmable operator facility does not trap VMCONIO-type or CP EMSGs produced by exit EXECs as it does for action routines.
The PROPPCHK EXEC is invoked when the programmable operator facility
determines that communication with a node that is being checked has changed sta­
tus. When this occurs, the following information is stacked, LIFO, for the EXEC.
1. Entries having the format
"nodeid up" or "nodeid DOWN" where:
nodeid is the RSCS nodeid of a node that has changed communication
status. UP indicates that the node had not been responding and has resumed
responding to acknowledgement requests. DOWN indicates that the node had been responding and has ceased respond­
ing.
2. Total number of nodeid entries stacked.
The PROPHCHK EXEC is invoked when the programmable operator determines
that communication with the logical operator node (if it is being checked) has
changed status. If the status has changed, a line is stacked LIFO for the EXEC.
The line is either "nodeid UP" or "nodeid DOWN", where "nodeid" is the RSCS
nodeid of the logical operator and "UP" and "DOWN" have the same meaning as
for PROPPCHK. If a virtual machine resource limit is reached, such as "disk-full", it may not be pos­
sible to write another record to the programmable operator facility log file. If this
happens, a user-written EXEC is invoked to perform whatever recovery action the
user thinks is desirable or necessary. The user EXEC must have the filename of
The Programmable Operator Facility 451

PROPLGER. The programmable operator facility stacks (LIFO) the error code
received from the CMS FSWRITE function. The programmable operator performs
the following actions depending on the return code from the EXEC.
RC = 0 recovered from error. The programmable operator facility should retry
logging. If it is still unable to log, an error message is sent.
RC = 4 unable to do recovery. The programmable operator facility should send
an error message.
The error message is sent to the logical operator. If the PROPLGER EXEC can­
not be found, the programmable operator facility acts as if RC = 4 has been
returned thus, an error message is sent to the logical operator. Whatever action is
taken, the programmable operator facility continues operation. The IBM-supplied
sample PROPLGER EXEC:
Closes the current log file • Sends the last two log files to the logical operator
Erases the last two log files.
If the same logging error occurs on two successive logging attempts, (for example,
two consecutive incoming messages cause the same logging error) the programma­
ble operator sets LOGGING to "OFF". This prevents unpredictable looping in
some situations. Note, though, that the logical operator may receive only two error
messages when logging errors occur.
Problem Determination -Debug Mode
Debug mode is used to perform problem determination on the programmable oper­
ator program itself. It allows responses to commands issued from the programma­
ble operator virtual machine console to be returned back to the console without
being intercepted by the programmable operator program. This permits any CP command (for example, CP TRACE and ADSTOP commands), to be issued with­
out having its response trapped by the programmable operator program.
SET DEBUG ON may be used after the programmable operator facility responds
with the message: PROP RUNNING -ENTER ' STOP , TO TERMINATE
indicating that the programmable operator facility is running and operational. The
programmable operator facility then responds with the message: PROP IS. RUNNING IN DEBUG MODE which is also written to the log file. Once in debug mode, the programmable opera­
tor facility waits to receive messages from another virtual machine, or for the sys­
tem programmer to enter input from the console. Since only two commands are
accepted from the programmable operator virtual machine console (STOP and
SET), to issue any CP commands the System Programmer must enter the CP envi­
ronment (using the PAl key). Otherwise, the commands are intercepted and
rejected as invalid prograrrmlable operator commands.
452 VM/SP System Programmer's Guide