Data communication service aids

Data communication service aids, such as Terminal communication task trace and DC Trace are described.

Terminal communication task trace
When an output device (such as a terminal, line, or node) hangs, you can use the terminal communication task trace to diagnose the problem.
DC trace
The data communication (DC) trace enables you to obtain information about the program flow within the communications analyzer and between the analyzer and the device dependent modules (DDMs).
Diagnosing problems in the Queue Control Facility Message Requeuer
The Queue Control Facility Message Requeuer (MRQ) processor module (DFSQMRQ0), which is part of the IMS Transaction Manager, provides diagnostic information for diagnosing errors while running the IBM® IMS Queue Control Facility for z/OS® (QCF).
Diagnosing message routing problems
User exits are consolidated into user exit DFSMSCE0. Several traces, messages, and information fields in the message prefix area can be used to diagnose message routing problems in the user exits and in IMS.
IMS transaction trace
The IMS transaction trace writes entries to the IMS log at entry to and exit from the DC call analyzer (DFSDLA30).
Receive-any buffer analysis
While talking with level 1 or level 2 IBM Software Support representatives, you might need to determine if you are out of receive-any (RECANY) buffers. Use either the IMS IPCS panel interface or the manual procedure to help you determine if this is the case. As you proceed through the steps, write down the information you gather.
Finding the active save set
To analyze data communication (DC) problems, you need to find the active save set at the time of abend.
IMS VTAM interface
The basic functions of an IMS DC operation are establishing communications, sending and receiving messages, and terminating communications. The execution of these functions is shared among the elements that make up the network: the terminal, the controller, the VTAM® system, the IMS system, and the application.
IBM 3270 error recovery analysis
When the IBM 3270 detects an error, it sends the processor one of four sense-status messages.
Diagnosing Message Format Service problems
The number of physical terminals traced and the number of lines traced can affect completeness of trace records and sequence of trace entries.
Message Format Service module traces
The Communications Interface Block (CIB) contains two module traces: CIBSTRAC and CIBTRACE.
Tracing errors in module DFSCNXA0
DFSCNXA0 is the interface module between IMS and VTAM for all logon processing and abnormal session termination processing. It is often the first module to be notified when a failure occurs on a session and is always the first to get control when a node connects to IMS.
IDC0 trace table entries
IDC0 trace table entries, including error messages issued by DFSCNXA0 are listed along with the codes and DFS message number.
APPC/IMS diagnostic aids
APPC/IMS diagnostic aids include LU manager trace, LU 6.2 module-to-code cross references, APPC/MVS verb-to-code cross references, DDFS1959e message information, diagnostic information for APP and OTMA with shared queues, and information on SNAPs and dumps.
OTMA diagnostic aids
OTMA diagnostic aids include OTMA trace, module-to-code cross references, verb-to-code cross references, DFS1296E message information, log records, and SNAPs and dumps.
Diagnosing Fast Path problems related to print data set options: IMS Spool API support
IMS provides an expansion of the DL/I application program interface that allows applications to interface directly to JES and create print data sets on the JES spool. These print data sets can then be made available to print managers and spool servers to serve the needs of the application.

Parent topic: Diagnosis