Subsystem parameter changes in Db2 13

You can use this information to plan for Db2 subsystem parameter changes at migration to Db2 13 and in continuous delivery.

Subsystem parameter changes in function level 501

The following changes take effect when you activate function level 500 in Db2 13. Function level 501 (V13R1M501) is the first opportunity after migration to Db2 13 for applications to use new features and capabilities that depend on catalog changes in Db2 13.

Subsystem parameter Change introduced Incompatible change?
UTILITY_HISTORY New subsystem parameter. No

For more information about these changes, see Function level 501 (Db2 13 installation or migration - May 2022).

Subsystem parameter changes in function level 500

The following changes take effect when you activate function level 500 in Db2 13. Activating function level 500 (V13R1M500) prevents coexistence with and fallback to Db2 12. Function level 500 is also the first opportunity for applications to use many of the new capabilities in Db2 13. However, new capabilities that depend on Db2 13 catalog changes remain unavailable.

Subsystem parameter Change introduced Incompatible change?
REORG_INDEX_NOSYSUT1 This subsystem parameter no longer influences use of the NOSYSUT1 behavior for the REORG INDEX utility with SHRLEVEL REFERENCE or SHRLEVEL CHANGE. The default value is also changed to YES, and it is protected value. No
STATPGSAMP This subsystem parameter also applies to the collection of inline statistics when the LOAD or REORG TABLESPACE utilities run with the STATISTICS keyword. No

For more information about these changes, see Function level 500 (for migrating to Db2 13 - May 2022).

Subsystem parameter changes in function level 100

The following changes take effect when you migrate to function level 500 in Db2 13. Db2 starts at function level 100 (V13R1M100) during migration to Db2 13, and fallback and coexistence with Db2 12 in data sharing remain possible. Many new capabilities in Db2 13 remain unavailable.

Subsystem parameter Change introduced APAR Incompatible change?
AUTHEXIT_CACHEREFRESH If the value is set to ALL and the z/OS® release is 2.5 or later, Db2 refreshes the entries in the plan authorization cache when a resource access on the plan object profile is changed in RACF® and the access control authorization exit (DSNX@XAC) is active. No
DDF The default value is changed to AUTO. No
DSMAX The range is expanded with the maximum value increased from 200000 to 400000. The existing default of 200000 is retained. No
EDM_SKELETON_POOL The default value is changed from 51200 to 81920 in KB. No
EDMDBDC The default value is changed from 23400 to 40960 in KB. No
FTB_NON_UNIQUE_INDEX The default value is changed from NO to YES. No
IRLMRWT IRLMRWT is now online changeable to support more granular specification of the lock timeout value. No
MAXCONQN The default value is changed from OFF to ON. No
MAXCONQW The default value is changed from OFF to ON. No
MAXSORT_IN_MEMORY The default value is changed from 1000 to 2000 (2 MB) in KB. No
NUMLKTS The default value is changed from 2000 to 5000. No
NUMLKUS The default value is changed from 10000 to 20000. No
OUTBUFF The default value is changed from 4000K to 104857600 (100MB). No
PAGESET_PAGENUM The default value is changed from ABSOLUTE to RELATIVE. No
SPREG_LOCK_TIMEOUT_MAX New subsystem parameter No
SRTPOOL The default value is changed from 10000 to 20000 (20MB) in KB.   No
STATIME_MAIN The default value is changed from 60 to 10. No
TABLE_COL_NAME_EXPANSION New subsystem parameter. No
ACCELERATION OPTIONS field (QUERY_ACCEL_OPTIONS subsystem parameter) New field on panel DSNTIP8A: 13 ENABLE ACCELERATOR SPECIFIC RESULTS PH48480 No

For more information about these changes, see Function level 100 (for migrating to Db2 13 - May 2022).

Removed subsystem parameters in Db2 13 (function level 100 and higher)

The following table lists subsystem parameters that are removed from this version of Db2 for z/OS. Refer to the information for the earlier version for detailed descriptions of the removed subsystem parameters.

Important: For best results, check the setting used in your Db2 12 environment, especially in data sharing environments. If the current setting does not match the setting listed in the following table, evaluate whether any other changes are needed to accept the new-behavior settings, before migrating to Db2 13.
Subsystem parameter Setting used in Db2 13 Description in earlier releases Incompatible change?
AUTHCACH 4K Specifies the size (in bytes per plan) of the authorization cache that is to be used if no CACHESIZE is specified on the BIND PLAN subcommand. No
DDF_COMPATIBILITY NULL

Controls certain characteristics of a connection between a client application and a Db2 for z/OS data server.

Yes
HONOR_KEEPDICTIONARY NO

Specifies whether Db2 honors the LOAD and REORG parameter KEEPDICTIONARY when tables are converted between basic row format and reordered row format.

No
DSVCI YES Controls whether Db2-managed data sets that are created by CREATE TABLESPACE or CREATE INDEX statements are to have variable VSAM control intervals. No
EXTRAREQ 100 Limits the number of extra DRDA query blocks that Db2 can request from a remote DRDA server. No
EXTRSRV 100 Limits the number of extra DRDA query blocks that Db2can return to a DRDA client No
IMMEDWRI NO Determines when updates to group buffer pool-dependent buffers are to be written to the coupling facility. No
IX_TB_PART_CONV_EXCLUDE YES Specifies whether to exclude trailing columns from the table-controlled partitioning keys when table spaces are converted from index-controlled partitioning to table-controlled partitioning. No
MAXARCH 10000

Controls the maximum number of archive log volumes that are to be recorded in the BSDS.

No
MAXTYPE1 0 Determines the number of inactive DBATs that Db2 is to allow. No
OPT1ROWBLOCKSORT DISABLE Specifies whether Db2 explicitly blocks sort operations when the OPTIMIZE FOR 1 ROW clause is specified on a query. No
PARA_EFF 50 Controls the efficiency that Db2 assumes for parallelism when Db2 chooses an access path. No
PLANMGMTSCOPE STATIC Specifies the types of SQL statements for applying the PLANMGMT subsystem parameter setting. No
REALSTORAGE_MANAGEMENT AUTO 1 Specifies whether Db2 should manage real storage consumption.
Important: Keep your current setting in Db2 12. See 1.)
No
RESYNC 2 Specifies the time interval, in minutes, between resynchronization periods. No
SUBQ_MIDX ENABLE Specifies whether to enable or disable multiple index access on some non-Boolean uncorrelated subquery predicates. No
TRACSTR NO Specifies whether the global trace starts automatically when Db2 starts. No
Notes:
  1. If you currently use a different setting, do not change the REALSTORAGE_MANAGEMENT setting to AUTO in Db2 12.

    Db2 13 uses enhanced automatic behavior for real storage management, which differs from the thread-based discard processing used with REALSTORAGE_MANAGEMENT=AUTO in Db2 12 or earlier.

    Db2 13 manages real storage discard processing at the system level to avoid z/OS RSM serialization from discard requests.