II14640: INFO APAR TO DOCUMENT AND CLARIFY CA RECLAIM SETTINGS FAQ

APAR status

• INTRAN

Error description

• CA RECLAIM was released with z/OS 1.12. CA RECLAIM is designed
  to actively manage the Control Areas (CA) within a VSAM data set
  that did contain records at one point in time, but have been
  emptied by ERASE requests on all of the records.
  CA RECLAIM sets these CAs to be reused whenever possible and
  is a planned improvement to to overall VSAM processing.
  .
  CA RECLAIM applies to VSAM KSDSes, AIXes and Catalogs. There is
  no CA RECLAIM processing for ESDS, RRDS, VRRDS or LINEAR data
  sets.
  .
  The default settings for CA RECLAIM are as follows:
  .
    IGDSMSxx CA_RECLAIM(NONE)
    DATACLASS CA-RECLAIM - Defaults to YES on z/OS 1.12
  .
  To enable CA-RECLAIM, do the following:
  .
    IGDSMSxx CA_RECLAIM(DATACLAS)
  .
  This will enable CA RECLAIM on that system.
  .
  NOTE:*****************
  At this point, all VSAM data sets that show a value of YES on a
  IDCAMS Listcat output: CA-RECLAIM(YES) are enabled for CA
  RECLAIM processing. All KSDS, AIX data sets and Catalogs, unless
  specified to CA-RECLAIM(NO) via an ALTER or that had a SMS
  DATACLASS assigned during allocation with CA-RECLAIM set to
  NO will show as YES.
  .
  Here is why:
  The value for a specific data set as shown by an IDCAMS listcat
  in addition to the value in the SMS parmlib for CA_RECLAIM is
  what is checked when CA RECLAIM processing is determining
  whether it should incur CA RECLAIM for a particular data set.
  The listcat value must be YES and the SMS parmlib value must be
  DATACLAS.
  .
  To disable CA RECLAIM for a data set you can use IDCAMS ALTER
  NORECLAIMCA to alter the CA-RECLAIM value for that data set. Or
  if you wish to enable CA RECLAIM for a data set you can use an
  IDCAMS ALTER RECLAIMCA. Note that with the PTF for OA35288 you
  can do either IDCAMS ALTER commands with a generic input to
  change a number of data sets with one command.
  .
  The value of YES or NO in the SMS DATACLASS is only used when a
  dataclass is assigned to a data set during define processing. If
  a dataclass is not assigned during define processing then the
  data set will default to a value of CA-RECLAIM(YES) when a data
  set is defined. Note that changing the value in the SMS dataclas
  will only affect any new defines. Any existing data sets with
  that dataclass will reflect the value in the SMS dataclass at
  the time of the define.
  .
  Depending on the age of VSAM data sets, you may have some data
  sets that are not eligible for CA RECLAIM show a value on a
  listcat of CA-RECLAIM(YES). Data sets created prior to the
  installation of the PTF for OA26256 on z/OS 1.10, or data sets
  created on z/OS 1.9 or earlier releases may show a value of
  CA-RECLAIM(YES) for ESDS, RRDS, LINEAR VRRDS data sets.
  Installation of the PTFs for apar OA36052 will correct the
  listcat output.
  .
  CA RECLAIM does require additional control blocks. Prior to the
  PTFs for OA36033 if the data set was eligible for CA RECLAIM the
  control blocks would be obtained, regardless of whether the SMS
  PARMLIB value for CA_RECLAIM was NONE or DATACLAS. This could
  result in applications receiving S878 abends even though CA
  RECLAIM  was disabled at the system level. The PTFs for OA36033
  will only obtain the control blocks at open time if the data set
  is eligible for CA RECLAIM and the SMS parmlib value of
  CA_RECLAIM is DATACLAS. If the setting of the SMS parmlib value
  of CA-RECLAIM is NONE when a data set that is eligible for CA
  RECLAIM is opened, then no control blocks will be obtained.
  However, if the SMS parmlib value is changed via the SETSMS
  command to DATACLAS, then if the control blocks will be
  obtained as needed for data sets that do not currently
  have them, but are eligible for CA RECLAIM.
  .
  There is a tool available that will produce a one line listing
  of data sets that are currently eligible for CA RECLAIM. While
  you can run an IDCAMS LISTCAT LEVEL or LISTCAT CATALOG to get
  a list of data sets, either of these will also produce a large
  amount of output and also list data sets that are not eligible
  for CA RECLAIM.
  This tool can be downloaded from the following FTP site:
  ftp://public.dhe.ibm.com/servers/storage/support/software/dfsms/
  It is on this site as CARECLAM.JCL.CNTL.TRSD. It will need to
  be downloaded in binary mode to a data set with the following
  DCB attributes: LRECL=1024,RECFM=FB,BLKSIZE=6144,DSORG=PS .
  After downloading it will need to be untersed using AMATERSE.
  Note that when untersing the output data set will be a PDS, so
  you need to supply directory blocks for the output data set when
  untersing. A space allocation of (TRK,(1,1,6)) should be fine.
  If you have questions or concerns about this tool open an ETR
  to component 5695DF106.
  
  IDCAMS LISTCAT changes for CA RECLAIM.
  The first is the addition of CA-RECLAIM(YES). This indicates
  that the data set is eligible for CA RECLAIM processing when
  opened.
  
  The second change is that when a RECLAIM of a CA occurs,
  as a result of an ERASE request, 1 will be added to the
  number of SPLITS-CA for the data component.
  
  In addition, if the 'new' CA used for a CA split in the 'add to
  end' PUT processing is a reclaimed CA, the SPLITS-CA count will
  will also be incremented; otherwise the 'add to end' CA split is
  is still not counted as in previous releases after apar OA38887
  is installed.
  
  Including both the CA reclaims and the 'add to end' CA splits
  when the new CAs are reclaimed CAs in the SPLITS-CA count is
  necessary for many VSAM applications such as those that need to
  be aware that the index structure has changed.
  
  This means you may see an increase in the number reported for
  SPLITS-CA for the data component over that reported for previous
  releases.
  
  
  The third change is that 1 is added to number of REC-DELETED for
  the index component for the data set. This reflects the total
  number of times CA RECLAIM has occurred for this data set.
  Taking the SPLITS-CA value from the data component and
  subtracting the REC-DELETED value from the index component will
  give the number of CA splits that have occurred for the data
  component.
  
  The fourth change is that the value of REC-INSERTED for the
  index component will indicate the number of CA's that have been
  been reused.
  
  This INFO APAR will be updated as necessary to reflect the most
  common questions and answers.
  .
  Additional information can also be found in the following
  manuals:
  .
  z/OS V1R12.0 DFSMSdfp Storage Administration (SC26-7402-14)
  7.3.6 Defining Shareoptions and RLS attributes for data class
  .
  z/OS V1R12 DFSMS Using Data Sets (SC26-7410-10)
  In Chapter 10 - Optimizing VSAM Performance
  2.5.3.3.2 Enabling and Disabling CA Reclaim
  

Local fix

• None.
  
  
  KEYWORDS:  CARECLAIM
  

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

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Fix information

Applicable component levels