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Milestone 11: Enablling Db2 support

If your site is not using—and does not plan to use—Xchange's Db2 support, you may skip this milestone and continue with Milestone-12-Enabling-IMS-support.

This milestone contains tasks for enabling Db2 support.

The roles involved are:Xchange Installer.

Overview

Xchange Db2 support provides date/time simulation for SQLetime functions while preserving the integrity and availability of Db2. With Db2 support enabled, Xchange will intercept Db2 special registers CURRENT DATE, CURRENT TIME, and CURRENT TIMESTAMP and return whatever values were specified on the Simulated Date Time Settings figure. Date, time, and timestamp columns defined as NOT NULL WITH DEFAULT will also be exchanged.

Xchange Db2 support is enabled by applying a USERMOD zap to the CSECT named DSNXVCTS in the IBM module DSNXGRDS. This CSECT is used solely for SQL date functions, so other Db2 dates are unaffected. The zapped module must be accessible to the Db2 database's (DBM) address space—for example in the STEPLIB. Cycling the address space may be necessary. Xchange Db2 Distributed Data Facility (DDF) support requires the same USERMOD zap. The zapped module must be accessible to the Db2 DIST address space—for example in the STEPLIB. Cycling the address space may be necessary.

Xchange Db2 Stored Procedure support requires the same USERMOD zap. The zapped module must be accessible to the Workload Manager (WLM) address space—for example in the STEPLIB. Cycling the address space may be necessary.

If Xchange fails during processing, its full recovery support prevents Db2 and the user application from abending and allows Db2 to perform its normal recovery and cleanup. Db2 returns a date of all asterisks to the caller and an SQL-187 return code just as it would if Xchange had not been involved.

Task 11.1: Apply the Db2 zap

We recommend that SMP/E be used to apply the Xchange Db2 zap. There are two advantages to using SMP/E:

  • If Db2 maintenance is later applied, you will be alerted to any regressions.
  • The zap can be easily removed with the SMP/E RESTORE function.

To apply the Db2 zap:

  1. Select the sample jobstream in CPWR.MLXGnnn.SLXGCNTL that corresponds to your site's Db2 release from the list in the following table.

Xchange DB2 Zap Members

Db2 Release

Sample Jobstream

Non-SMP

SMP/E

6.1

XGDB2A61

XGDB2S61

7.1

XGDB2A71

XGDB2S71

8.1

XGDB2A81

XGDB2S81

9.1

XGDB2A91

XGDB2S91

10.1

XGDB2AA1

XGDB2SA1

11.1

XGDB2AB1

XGDB2SB1

12.1

XGDB2AC1

XGDB2SC1

13.1

XGDB2AD1

XGDB2SD1

Both jobstreams for each Db2 release point to a common zap member, XGZPDBxx, found in the CPWR.MLXGnnn.SLXGDATA PDS. The xx corresponds to the final two digits of the jobstream.

  1. Before applying the zap by running the appropriate job, either comment out or uncomment the EXPAND statement on the first line of XGZPDBxx as follows:
    1. For SMP/E, replace the asterisk (*) in position 1 with a blank.
    2. For non-SMP, make sure an asterisk is in position 1.

  2. Apply the zap.

    Important

    Sites with Db2 can now use the Xchange batch demonstration program XGBCHDB2 previously compiled and link edited in Milestone-9-Assembling-or-compiling-and-link-edit-test-programs.

    Sites with Db2 and CICS can now use the Xchange demonstration program XGCDB2.

 

Tip: For faster searching, add an asterisk to the end of your partial query. Example: cert*