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Function level 504 verifies earlier new-function APARs in Db2 13 for z/OS

By Paul McWilliams posted Tue December 05, 2023 04:37 PM


By Paul McWilliams and John Lyle.

Starting with the availability of function level 504 in Db2 13, activating a higher function level now also verifies that a specific set of previously available PTFs for new-function APARs are applied consistently in your Db2 13 environment, including all data sharing members. This change applies specifically to PTFs for “new-function” APARs that introduce external changes to Db2 that are not otherwise associated with or controlled by any Db2 function level. 

Hopefully, you are aware by now that the single Db2 for z/OS service stream now includes many new-function APARs for the continuous delivery of new function to Db2 13. Some of these APARs introduce deactivated code for use in future function levels, and others enable the activation of new function levels. However, many new-function APARs in Db2 13 introduce external changes that take immediate effect when you apply the PTF on each data sharing member. That is, their external changes are not controlled by activation of any Db2 function level or an application compatibility level. Db2 development uses this approach only when the external changes being made do not require consistent behavior from every member of a Db2 data sharing group. 

Although such changes can safely take effect as the PTF is applied on each Db2 data sharing member, independent software vendors (ISVs) and customers have requested a way to know when they can rely on the consistent presence of such behavior changes in their Db2 13 environments. 

Our solution for this request is simpler than you might expect. We identified the list of the existing Db2 13 APARs with PTFs that introduce external changes with vendor impact up to certain cutoff date. Then we included each of these APARs in the PREREQS list for APAR PH54919, which is the APAR that enables activation of function level V13R1M504. 

The result is that these APARs are guaranteed to be applied on all members after activation of function level 504. And perhaps more importantly, these PTFs cannot be removed after function level 504 or higher is activated. 

You might also realize that you can check if all these PTFs are applied, even before the function level is activated, by looking at the Db2 code level in the DISPLAY GROUP command output. However, it is important to remember that the prerequisite PTFs for a function level can still be removed up until the function level is activated. That’s why we say that activation verifies that these APARs are applied.

You can find out which function level verifies each new-function APAR by looking at the new “Verifying function level” column in the table in New-function APARs for Db2 13. Any APARs with a blank value in this column are not yet in the PREREQs for a function level and they will be added to the PREREQS list for the next function level. 

Since function level 504 is our first time using this approach, we need to create a foundation going forward, so the PREREQS list for PH54919 includes many APARs. However, we expect future function levels to include only APARs not in the PREREQS list for the previous function level, so the PREREQs lists for future function levels going forward are likely to include smaller numbers of APARs.