Extended diagnostic mode

The PlexManager extended diagnostic mode (XDM) can be used to collect additional diagnostic data for problems found in the CAS, CMAS, or TSO user address space. Specifically, XDM provides:

To activate XDM mode in the CAS or CMAS, update their respective start-up procedures by adding XDM=Y on the EXEC statement. To activate XDM mode in the TSO address space, specify XDM=YES when the CAS Connection ISPF Panel is displayed.

Status messages

When XDM is active, the following messages can be issued to the console:

BBMSD801I Module - xxxxxxxx not found. Conditional PGLOAD request failed
This message is issued whenever a conditional MSD_PGLOAD request fails.
BBMSD900E TCB AT xxxxxxxx HAS ABNORMALLY TERMINATED - CODE=tnn
This message is issued any time a task abends.
BBMZE989I CONTROL TASK (nnnn) RESOURCE RECOVERY COMPLETE - jobname(jesjobid)
This message is issued whenever a control task for any connected address space goes through end of task processing.
BBMZE999I GLOBAL RESOURCE RECOVERY COMPLETE - jobname(jesjobid)
This message is issued whenever any connected address space goes through end of memory processing.

In addition to these extra diagnostic messages, all abends are documented with LOGREC, SDUMP, and recovery manager messages.

If the General Services Interface (GSI) router returns a failure code with a level higher than WARNING and the GSI requester is not a local server initialization function, a snap trace and dump of the failing CSRB and FPB are produced. The snap trace and dump consist of messages like these:

BBMLD001E GSI service failed - Completion code=8
BBMLD002E GSI call issued at 85112B96 (MXC42+0452 in control section MXC40)
BBMLD003E CSRB at 7F418F7C; ROUT=01010415 / ZERR=07D33212 / FPBA=7F4D017C
BBMLD004E FPB data  0000  0000007C 00000038 15000000 7F455AF0
BBMLD004E ........  0010  00000008 07D33212 07080200 7F4D017C
BBMLD004E ........  0020  00000000 7F455398 01010200 01049C00
BBMLD004E ........  0030  00000000 00000000 00000000 7F455AF0

Internal tracing

Enabling XDM activates the internal linkage trace in a CAS. The linkage trace is kept in ECSA in 4K blocks. It keeps track of both assembler and C services:

If XDM is active, the linkage trace also causes the creation of storage manager and environment performance instrumentation GTF records. These GTF records help in determining performance-related problems.

Note:
To activate fully the creation of these GTF records, SMGTF=Y must also be specified in the CAS startup procedure.

Disabling error recovery

During normal system operation, CICSPlex® SM does everything it can to prevent critical services, such as the storage manager and the program manager, from terminating. However, when XDM mode is active, these services abend in cases that would normally produce a bad return code.

For example, the storage manager normally passes back a warning completion code in the following conditions:

With XDM active, all of these conditions result in an error completion code. Also, if an error occurs during component initialization or termination, the controller is terminated.

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