IMS Connectivity in an On Demand Environment: A Practical Guide to IMS Connectivity

Chapter 19. Open Database Access 375

IMS DB manager performance carefully and possibly take appropriate tuning actions when

you find performance problems.

19.5.5 RRS logging performance

Because of the use of RRS, ODBA performance is related to the RRS logging performance.

RRS uses z/OS logger and five log streams that can be shared by multiple systems in a

sysplex. You have several choices of the z/OS logger implementation; you must consider that

your choice should meet your performance and recovery requirements. For a description of

configuring and defining RRS logging requirements, see z/OS V1R6.0 MVS Programming:

Resource Recovery, SA22-7616.

19.6 Problem determination

Whenever your program terminates abnormally, you can take some actions to simplify the

task of finding and fixing the problem. You already might have guidelines about what you

should do if your program terminates abnormally. The suggestions given here are some

common installation guidelines. Document the error situation to help in investigating and

correcting it. Here is some of the information that can be helpful to document:

 Abends, return codes, or reason codes.

 Helpful messages: Depending on how your environment is set up, you might have to

search the client location, local ODBA application messages, local z/OS messages (WLM,

RRS, system), or the IMS subsystem.

 The program's PSB and PCB name.

 The call function.

 The contents of the application interface block (AIB).

 The contents of the I/O area when the problem occurred.

 The status of the database being accessed (stopped?).

 The date and time of day.

When your program encounters an error, it can pass all the required error information to a

standard error routine.

You can send a message to the system log by issuing a LOG request.

19.6.1 Finding the problem

If your program does not run correctly, you need to isolate the problem. The problem might be

anything from a programming error (for example, an error in the way you coded one of your

requests), to a system problem. This section provides some guidelines about the steps that

you, as the application programmer, can take when your program either fails to run,

terminates abnormally, or gives incorrect results.

19.6.2 IMS initialization errors

Before your program receives control, IMS must have correctly loaded and initialized the PSB

and DBDs used by your application program:

 Check for IMS error messages.