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