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

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

 Issue a /DIS PGM (psbname) and /DIS DB (dbname) to check the status of the IMS

resources you need.

 Check to see if there have been any recent changes to the DBDs, PSBs, ACBs, or the IMS

system maintenance.

If you have a problem is in this area, you might need to talk to a DBA or IMS system

personnel (or the equivalent specialist at your installation) to help with the problem.

19.6.3 Running errors

If you do not have any IMS initialization errors, check the following areas in your program:

 The output from the compiler. Make sure that all error messages have been resolved.

 The output from the linkage editor:

– Are all external references resolved?

– Have all necessary modules been included?

– Was the language interface module correctly included?

 Your JCL: Is the information that described the files that contain the databases correct? If

not, check with your DBA.

 If the program stalls and must be cancelled, check that there are CMIT/DPSB calls prior to

a new APSB for the same databases.

19.6.4 The application interface block

For an explanation of the application interface block (AIB), refer to 19.4.3, “The application

interface block (AIB)” on page 368. Always check the IMS status code, the reason code, and

the return code after an IMS call. The reason code is contained in the AIBREASN field, and

the return code is contained in the AIBRETRN field. Check for non-zero values for the reason

and return codes, and unexpected non-blank spaces for the status code (for example, GE and

GB might be valid status codes indicating no more segment found, or end of database

reached).

19.7 IBM-supplied ODBA infrastructures

You do not have to code an ODBA application by yourself, because IBM provides several

ODBA applications to meet your requirements. These ODBA applications work as

infrastructure to execute your business logic that access to IMS databases. You can code the

business logic by using various API such as DL/I or SQL through ODBC and JDBC interfaces,

and you can run it on any platforms. In this section, we introduce the following IBM-supplied

ODBA infrastructures.

19.7.1 DB2 stored procedure

The ODBA interface allows a DB2 stored procedure to directly connect to an system and

issue DL/I calls to access IMS databases. A stored procedure can issue database DL/I

requests through an ODBA callable interface. You need to update the startup procedure for

the WLM-established stored procedure address space to add the ODBA data set names to

the STEPLIB and DFSRESLB concatenations. Figure 19-5 on page 364 shows the general

structure of ODBA from a DB2 stored procedure. After you have coded your stored procedure

containing the logic for IMS database access, you can call this stored procedure from any

platform that can access DB2 for z/OS stored procedure environment.