6. Database Tailoring and Retrofitting Techniques › 6.2 Tailoring the Database › 6.2.2 Tailoring Database Files › 6.2.2.4 Change a File's Compression Eligibility

6.2.2.4 Change a File's Compression Eligibility

To change a file's compression eligibility, do the following:

o Review the COMPRESS statement specification that follows
  the FILE statement in sharedprefix.MICS.GENLIB(cccGENIN).

  If it contains Ns for all timespans and the comment
  "(FILE COMPRESSION NOT SUPPORTED)", do NOT change this
  specification and do not try to compress this file.

  The COMPRESS parameter is generated into
  sharedprefix.MICS.GENLIB(CMPRSDEF) by the cccCGEN job.
  Each database unit's COPYLIBU job adjusts the unit's
  prefix.MICS.PARMS(COMPRESS) for new products.  Once the
  COMPRESS member FILE statement exists, COPYLIBU will not
  update it.

o To help you achieve your space savings goal, use the
  CA MICS Administrator Utilities.

  - Run the Candidacy report (MWF;5;4;1).

  - Review the report and choose a compression threshold.

  - Run the Recommendation report (MWF;5;4;2).

  - Review the results.  The tabular report shows the effects
    of compression at the threshold you chose.  The
    recommended statements for your COMPRESS member in
    prefix.MICS.PARMS are also provided, as is information
    about current and projected database size.

o Review and edit the statements in the COMPRESS parameter
  library (prefix.MICS.PARMS):

  Note:  only do so if the COMPRESS statement in
         sharedprefix.MICS.GENLIB(cccGENIN) indicates that
         the file can be compressed (that is, the comment
         "FILE COMPRESSION NOT SUPPORTED" is not present on
         the COMPRESS statement).

  - Edit the DBCOMPRESS statement to enable the file to be
    compressed by setting DBCOMPRESS ON ALL or DBCOMPRESS ON
    ccc for the product whose file you want compressed.

  - If the file you want to compress is an intermediate file
    (its FILE statement in sharedprefix.MICS.GENLIB has a
    file type of 50, 51, or 52), edit the IFCOMPRESS
    statement to enable the intermediate file to be
    compressed by setting IFCOMPRESS ON ccc.

  Note:  only do so if the COMPRESS statement in
         sharedprefix.MICS.GENLIB(cccGENIN) indicates that
         the file can be compressed (that is, the comment
         "FILE COMPRESSION NOT SUPPORTED" is not present on
         the COMPRESS statement).

  - Edit the FILE statement to enable compression in the
    timespans you desire by setting the timespan indicators
    to Y (enabling compression) or N (disabling compression).

    Remember that changing a specification from Y to N means
    that your online databases for that timespan will
    require more DASD.  Ensure that there is adequate space
    in that timespan's data set to accommodate the growth to
    avoid B37 and D37 abends in the operational jobs.

    Do NOT add FILE statements to the COMPRESS parameter
    library member.  If you add COMPRESS statements to
    cccGENIN members, run COPYLIBU to insert new FILE
    statements in the COMPRESS parameter library member.

o Run the CYCLEGEN job for the unit to activate your new
  specifications.  CYCLEGEN resides in the prefix.MICS.CNTL
  data set.

o Data compression starts with the 01 cycle of the next
  DAILY job.

o To fully achieve space savings, compress the old cycles
  following these steps:

  - Back up your current CA MICS unit libraries using the
    Operational Status and Tracking BACKUP command or by
    executing the batch BACKUP job.

  - Delete your current CA MICS unit libraries and reallocate
    them using the ALLOCATE job and specifying the new
    database's size from information provided on the
    Recommendations tabular report.

    Factor in room for growth to prevent out-of-space abends
    in the future.

  - Restore your new specifications to your reallocated unit
    libraries using the Operational Status and Tracking
    RESTORE command or by executing the batch RESTORE job.