THRESHLD

The THRESHLD option allows you to specify a threshold value, in kilobytes, above which the utility applies secondary values to allocated data sets.

Related topic

Dynamic-allocation-options

THRESHLD.png

The utility tests this threshold for each data set to be allocated. If the size for a particular data set is greater than the threshold, the utility performs the following tasks:

  • When SMS is NO, the utility uses the secondary values of the following options for the allocated data sets:
    • UNIT (unit name)
    • UNITCNT (unit count)
    • VOLCNT (volume count)
    • AVGVOLSP (average volume space)
    • MAXEXTSZ (extent size)
    • DSNTYPE (data set type), unless DSNTYPE is EXTREQ or EXTPREF
  • When SMS is YES, the utility uses the secondary values of the following options (or passes them to SMS if applicable):
    • STORCLAS, MGMTCLAS, or DATACLAS (the class name for the SMS classes)
    • VOLCNT (volume count)
    • AVGVOLSP (average volume space)
    • DSNTYPE (data set type)
    • If SMSUNIT is YES
      • UNIT (unit name)
      • UNITCNT (unit count)

If you specify 0, or if the threshold is not exceeded, the utility uses the primary values for these options.

Tip

If you use THRESHLD to send larger data sets to tape, consider setting the MAXTAPE option to limit the number of tapes that you use.

DSNUTILB reorganization jobs

When invoking DSNUTILB, the utility handles this option differently, depending on the type of data set that you are allocating:

  • For copy data sets, the utility translates this option to a LIMIT value in the TEMPLATE control statement that it builds for the corresponding IBM utility. The utility also builds the secondary TEMPLATE control statement to which the IBM utility will switch when the LIMIT is exceeded.

    The utility assumes that the value that you supply for THRESHLD is in kilobytes and translates that value to the appropriate value and unit of measure for the LIMIT keyword. Note the following additional information about this value:

    • The utility rounds down to the nearest whole value.
    • If you specify a value that would cause the utility to translate to a value less than 1 cylinder, the utility builds the template with a LIMIT value of 1 CYL.
  • For all other data sets, the utility ignores this option.

Examples

The following examples illustrate how to use THRESHLD for different types of scenarios. In example 1, all allocated data sets for this DDTYPE go to SYSDA:


THRESHLD example 1
UNIT(SYSDA)
THRESHLD 0

 In example 2, allocated data sets with a size greater than 720 MB for this DDTYPE go-to unit LARGE. Smaller allocated data sets for this DDTYPE go-to unit WORK:

THRESHLD example 2
UNIT(WORK,LARGE)
THRESHLD 720000

 In example 3, data sets for this DDTYPE are SMS-managed. Allocated data sets with a size greater than 72 MB go to STORCLS2, MGMTCLS2, and DATACLS2. Smaller data sets go to the classes specified in the first parameter of each class type.

THRESHLD example 3
SMS YES
STORCLAS(STORCLS1,STORCLS2)
MGMTCLAS(MGMTCLS1,MGMTCLS2)
DATACLAS(DATACLS1,DATACLS2)
THRESHLD 72000

In example 4, the utility allocates data sets with the following properties for this DDTYPE:

  • Data sets with a size less than or equal to 7,200 MB go-to unit SYSDA. The maximum volume count is calculated based on an average volume usage of 30,000 tracks.
  • Data sets with a size greater than 7,200 MB go-to unit CART with no more than 25 volumes.
THRESHLD example 4
VOLCNT(AUTO,25)
AVGVOLSP((30000,TRK),(900000,TRK))
UNIT(SYSDA,CART)
THRESHLD 7200000

Specifying the default

You can specify the default for the THRESHLD command option in your installation options module by using the THRESHLD installation option. The utility was shipped with a default value of 0 for this option. The command option overrides the default that is in the installation options module.


 

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