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- ALTERNATEINDEX
- Defines an alternate index or recatalogs an alternate index
entry.
The ALTERNATEINDEX keyword is followed by the parameters
for the alternate index as a whole. These parameters are enclosed
in parentheses and, optionally, are followed by parameters given separately
for the DATA and INDEX components.
Abbreviation: AIX
- NAME(entryname)
- Is the alternate index's entryname or the name of each of its
components. The entry name specified for the alternate index as a
whole is not propagated to the alternate index's components.
You
can define a separate entry name for the alternate index, its data
component, and its index component. If you do not give a name for
the data or index component, one is generated. For more information
about the system-generated name format, see z/OS DFSMS Managing Catalogs.
When
the alternate index, data component, and index component are individually
named, each can be addressed.
- RELATE(entryname)
- Names the alternate index base cluster. The base
cluster is an entry-sequenced cluster or a key-sequenced cluster to
which the alternate index is to be related. You cannot relate an alternate
index to a reusable cluster, to a relative record cluster, to an extended
addressability ESDS, or to a VVDS (data set name 'SYS1.VVDS.Vvolser').
An SMS-managed alternate index has the same management class and storage
class as its base cluster.
Select the entryname so that
the multilevel alias facility selects the same catalog as the one
containing the related data set name.
Abbreviation:
REL
- CYLINDERS(primary[ secondary])|
- KILOBYTES(primary[ secondary])|
- MEGABYTES(primary[ secondary])|
- RECORDS(primary[ secondary])|
- TRACKS(primary[ secondary])
- Is the amount of space in cylinders, kilobytes, megabytes, records,
or tracks allocated to the alternate index from the volume's available
space. A kilobyte and megabyte allocation resolves to either tracks
or cylinders; records are allocated to the nearest track boundary.
Exception: If allocation resolves to tracks, the
space is contiguous. For more information, see z/OS DFSMS Using Data Sets.
Requests for space are directed to DADSM and result in
a format-1 DSCB for the data and index component entries.
If you do not use the MODEL parameter or the RECATALOG
parameter, you must include one, and only one, of these parameters:
CYLINDERS, KILOBYTES, MEGABYTES, RECORDS, or TRACKS.
The
space parameter is optional if the cluster is SMS-managed, but if
you do not use it, space can be modeled or defaulted by SMS. If it
is not determined, the DEFINE is unsuccessful.
To
maintain device independence, do not use the TRACKS or CYLINDERS parameters.
If you do not use TRACKS or CYLINDERS for an SMS-managed alternate
index, space is allocated on the volume selected by SMS.
When you do not divide the data component into key ranges,
and more than one volume is given, the primary amount of space is
allocated only on the first volume when the component is defined.
When the component increases to extend to additional volumes, the
first allocation on each overflow volume is the primary amount.
Secondary amounts can be allocated on all volumes available
to contain parts of the alternate index, regardless of the key ranges
when the alternate index is extended.
You can include
the amount of space as a parameter of ALTERNATEINDEX, as a parameter
of DATA, or as a parameter of both DATA and INDEX: - If the space is specified as a parameter of ALTERNATEINDEX, the
amount specified is divided between the data and index components.
The division algorithm is a function of control interval size, record
size, device type, and other data set attributes.
If the division
results in an allocation for the data component that is not an integral
multiple of the required control area size, the data component's allocation
is rounded up to the next higher control area multiple. This rounding
can result in a larger total allocation for your alternate index than
what you specified.
- If the space is specified as a parameter of DATA, the entire amount
given is allocated to the data component. An additional amount of
space, depending on control interval size, record size, device type,
and other data set attributes, is allocated to the index component.
To determine the exact amount of space allocated to each
component, list the alternate index's catalog entry, using the LISTCAT
command.
The primary and each secondary allocation must be able to be satisfied within
five extents; otherwise, your DEFINE or data set extension is unsuccessful.
You can use
these keywords for both SMS-managed and non-SMS-managed data sets. - primary
- Allocates the initial amount of space to the alternate index.
- secondary
- Allocates the amount of space each time the alternate index
extends, as a secondary extent. If the secondary space allocation
is greater than 4.0 gigabytes, it is reduced to an amount as close
to 4.0 GB as possible, without going over. This is not true for extended
addressability data sets, which have no such space limitation. When
you use secondary, space for the alternate index's data and index
components can be expanded to a maximum of 123 extents.
Abbreviations: CYL, KB, MB,
REC, and TRK
- VOLUMES(volser[ volser...])
- Specifies the volumes on which an alternate index's components
are to have space. This parameter is not required if the cluster is
modeled or if the cluster is SMS-managed. You can specify VOLUMES
for SMS-managed data sets; however, the volumes specified might not
be used and, in some cases, can result in an error.
For SMS-managed
data sets, you can use up to 59 volumes. If the combined number of
volumes for a cluster and its associated alternate indexes exceeds
59, unpredictable results can occur.
You can let SMS choose
the volumes for SMS-managed data sets by coding an * for the volser
with the VOLUMES parameter. If both user-specified and SMS-specified
volumes are requested, the user-specified volser must be input first
in the command syntax. The default is one volume.
If you do
not use the MODEL parameter, VOLUMES must be placed as a parameter
of ALTERNATEINDEX, or as a parameter of both DATA and INDEX.
If
the data and index components are to reside on different device types,
you must include VOLUMES as a parameter of both DATA and INDEX. If
more than one volume is listed with a single VOLUMES parameter, the
volumes must be the same device type.
You can repeat a volume
serial number in the list only if you use the KEYRANGE parameter.
This can place more than one key range on the same volume. However,
repetition is valid only if all duplicate occurrences are used for
the primary allocation of some key range.
The VOLUMES parameter
interacts with other DEFINE ALTERNATEINDEX parameters. Ensure that
the volumes you define for the alternate index are consistent with
the alternate index's other attributes: - CYLINDERS, RECORDS, TRACKS: The volumes contain enough
available space to satisfy the component's primary space requirement.
- FILE: To define an alternate index, the volume information supplied
with the DD statement pointed to by FILE must be consistent with the
information listed for the alternate index and its components.
Abbreviation: VOL
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