DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

4.12.1 Unicode IFCIDs
In this section we describe the significant enhancements to DB2 instrumentation in V8,
paying special attention to the new IFCIDs that provide detailed information to help you
monitor and tune your DB2 environment.
DB2 V8 introduces a new DSNZPARM parameter, UIFCIDS, which governs whether output
from IFC records should include Unicode information.
DB2 V8 supports a Unicode catalog and long names, also in Unicode. This means that DB2
object names, for example table names, can be longer than before and use “special” Unicode
characters. Normally the various DB2 identifiers that are externalized in IFCID records are
converted to EBCDIC. This is done to make it easier for applications that read IFCID records,
like online monitors, to provide “toleration support” for DB2 V8.
Only a subset of the character fields is encoded in Unicode. The remaining fields maintain the
same encoding of previous releases, EBCDIC. The fields that can be written as Unicode are
identified in the IFCID record in the DSNDQWxx mapping macros which are shipped in the
SDSNMACS dataset. Each field is identified by a %U in the comment area to the right of the
field declaration.
All of the information that is presented in the IFCID records in Unicode are stored in Unicode
in memory. If you choose to have your IFCID records continue to contain only EBCDIC data,
each of those data elements must be converted to EBCDIC from Unicode. See 4.7, “Unicode”
on page 174 for more information.
4.12.2 Statistics enhancements
In this section we discuss the IFC enhancements related to storage trace records that can be
obtained through the statistics trace.
Enhanced DBM1 and z/OS storage usage reports
Additional fields were added to storage-related IFCIDs 225 and 217 for 64-bit addressing.
Sample DB2 Performance Expert (PE) statistics trace reports, showing the IFCID 225 record,
are discussed in more detail in 4.2, “Virtual storage constraint relief” on page 139. IFCID 217
has more detailed information, but is normally only used under the guidance of the IBM
Support team, so it is not discussed in more detail in this publication.
In addition, IFCID 225 and 217 have been added to monitor class 1 and are available via IFI
READS requests.
Additional high water mark counters in statistics records
DB2 V8 adds the following high water mark counters to the statistics record, which should
assist you in more accurately setting the appropriate DSNZPARM parameters:
► Q3STHWIB - High water mark for IDBACK, the number of background connections
► Q3STHWIF - High water mark for IDFORE, the number of foreground connections
► Q3STHWCT - High water mark for CTHREAD, the number of active threads
These fields are also reported in DB2 Performance Expert (DB2 PE) statistics reports, in the
Subsystem Services section, as shown in Example 4-4.
Example 4-4 DB2 PE enhanced subsystem services reporting
SUBSYSTEM SERVICES QUANTITY /SECOND /THREAD /COMMIT
Chapter 4. DB2 subsystem performance 205