Dataset Define Cluster dialog box

You use this dialog to issue an IDCAMS DEFINE CLUSTER command to define attributes for a cluster as a whole and for the components of a cluster.

The Options tab of this dialog box provides the following options in three tabbed subsections: the Cluster tab, the Data tab, and the Index tab. These tabs correspond to the cluster that you define and its data and index components. You specify many of the same attributes for each of the three entities (cluster, and its data and index components). The values that you specify are unique to each entity.

To learn about the standard capabilities of a dialog box, see Standard tabs in the dialog boxes of the Storage Toolkit. The topic includes a link to the Reference guides for commands that are used in the Storage Toolkit.

Table 1. IDCAMS DEFINE CLUSTER options that are available in the Dataset Define Cluster dialog box of the Storage Toolkit. Part 1 of 3, Cluster options
Option Description
Fully Qualified Name Type the fully-qualified entryname for the cluster. This name is not propagated to the DATA and INDEX components of the cluster. For SMS and non-SMS-managed clusters, the component names must resolve to the same catalog as the cluster name of the data set. You can define a separate entryname for the cluster, its data component, and its index component. If no name is specified for the data and index component, a name is generated. When the cluster, data component, and index component are individually named, each can be addressed.
Fully Qualified Model Type the fully-qualified name of the cluster that you want to use as a model.
Space Units Select the unit of space that you want to allocate in the volume. Options include cylinders, kilobytes, megabytes, records, or tracks. Then specify a corresponding value for the unit that you selected. The Primary value that you specify allocates the initial amount of space to the cluster. The Secondary value that you specify allocates an amount of space for each time the cluster extends.
Volser(s) Specifies the volumes on which a cluster is to have space. The maximum number of VOLSERs is 59. Choose one of the following values in the list:
  • The serial number of an eligible direct access volume on which a new cluster is to be located

    OR

  • The serial number of a direct access volume on which an old cluster is located.

    If you choose an old cluster for Volser, the cluster must be on the specified volume for allocation to take place. If you do specify a value for Volser, the system allocates new clusters to any eligible direct access volume.
Control interval size The size of the control interval for the cluster.
Buffer space Specifies the minimum space for buffers. If you do not specify a value, VSAM attempts to get enough space to contain two data component control intervals and, if the data is key-sequenced, one index component control interval.
Data class Identifies the name (1-to-8 characters) of the data class for the data set. This metric provides the allocation attributes for new data sets.
Account Specify up to 32-bytes of accounting information and user data for the data set. The information is supported for only SMS-managed VSAM and non-VSAM data sets. The information is used only for the data set level (not member level) of PDSE/PDS.
Management class For SMS-managed data sets, you can type the name of the management class for a new data set.
Owner Type the name of the owner of the cluster.
Storage class For SMS-managed data sets, you can type the name of the storage class. Your storage administrator defines the range of names that you can use for storage classes.
Catalog Type the name of the catalog in which you want to define the entry.
Erase Specifies that the cluster is overwritten with binary zeros when its entry in the catalog is deleted.
Recatalog Select this option to cause the catalog entries for the cluster components to be re-created from information in the VVDS, if valid VVDS entries are found on the primary VVDS volume.
Reuse Select this option to enable the cluster to be opened repeatedly as a reusable cluster.
Spanned Select this option to enable a data record to cross the boundaries of a control interval. If the maximum length of a data record (as specified with RECORDSIZE) is larger than a control interval, the record is contained on more than one control interval. This option allows VSAM to select a control interval size that is optimal for the DASD. You cannot use this option in the definition of a linear data set cluster.
Speed Select this option to prevent preformatting of the control areas of the data component during loading (creation) of a data set.
Data organization type By default, the data organization type is set to Indexed. Use this option to specify the type of data organization for the cluster: Indexed, Linear, Non-indexed, or Numbered.
Table 2. IDCAMS DEFINE CLUSTER options that are available in the Dataset Define Cluster dialog box of the Storage Toolkit. Part 2 of 3, (optional) Data component options
Option Description
Fully Qualified Name Type the fully-qualified name of the data component.
Fully Qualified Model Type the fully-qualified name of the data component that you want to use as a model.
Space Units Select the unit of space that you want to allocate in the volume. Options include cylinders, kilobytes, megabytes, records, or tracks. Then specify a corresponding value for the unit that you selected. The Primary value that you specify allocates the initial amount of space to the data component. The Secondary value that you specify allocates an amount of space for each time the data component extends.
Volser(s) Specifies the volumes on which a component is to have space. The maximum number of VOLSERs is 59. Choose one of the following values in the list:
  • The serial number of an eligible direct access volume on which a new component is to be located

    OR

  • The serial number of a direct access volume on which an old component is located.

    If you choose an old component for Volser, the component must be on the specified volume for allocation to take place. If you do specify a value for Volser, the system allocates new components to any eligible direct access volume.
Control interval size The size of the control interval for the component.
Buffer space Specifies the minimum space for buffers. If you do not specify a value, VSAM attempts to get enough space to contain two data component control intervals and, if the data is key-sequenced, one index component control interval
Record Size Specifies the average and maximum lengths, in bytes, of the records in the data component. The minimum record size is 1 byte.
  • Nonspanned records: For nonspanned records, the (maximum record size + 7) total cannot exceed the size of the control interval of the data component. In this case, the default values for Average and Maximum are 4089 and 4089, respectively.
  • Spanned records: When you use a record size that is larger than one control interval, you must also select the Spanned option in the Cluster tab. In this case the default values for Average and Maximum are 4086 and 32600, respectively.
Free Space Specifies the percentage of each control interval (CI) and control area (CA) to be set aside as free space when the cluster is initially loaded or when a mass insert is done. The value of CI% is the percentage of space to be preserved for adding new records and updating existing records with an increase in the length of the record.

Because a CI is split when it becomes full, the CA might also need to be split when it is filled by CIs created by a CI split. The empty space in the control interval and control area is available for data records that are updated and inserted after the cluster is initially loaded.

This parameter applies only to key-sequenced clusters, and variable-length relative records with variable-length records. CI-percent is the number of bytes that is equal to, or slightly less than, the percentage value of CI-percent. CA-percent is the number of control intervals equal to, or less than, the percentage of CA-percent.
Share Options These settings determine how a component or cluster can be shared among users. To ensure integrity, you should be sure that share options specified at the DATA and INDEX levels are the same.
  • Cross Region: Specifies the amount of sharing allowed among regions within the same system.
  • Cross System: Specifies the amount of sharing allowed among systems. Job steps of two or more operating systems can gain access to the same VSAM data set regardless of the disposition indicated in the DD statement for the data set in each step.
For information regarding the options, see the description of the IDCAMS DEFINE CLUSTER command consult DFSMS Access Method Services for Catalogs. A general link to this documentation is provided in Table 1.
Keys In this area, you can specify information about the prime key field of a key-sequence data records of a data set. This parameter applies only to key-sequenced clusters. The default is a key field of 64 bytes, beginning at the first byte (byte 0) of each data record. The key field of the cluster's index is called the prime key to distinguish it from other keys, called alternate keys.
  • Length: Specifies the length of the key.
  • Offset: Specifies the displacement of the key (in bytes) from the beginning of the record. The sum of length plus offset cannot exceed the length of the shortest record. The length of the key can be 1 to 255 bytes.
Erase Select this option to cause components to be overwritten with binary zeros when their entries in the catalog are deleted.
Reuse Select this option to enable the component to be opened repeatedly as a reusable cluster.
Spanned Select this option to enable a data record to cross the boundaries of a control interval. If the maximum length of a data record (as specified with Record Size) is larger than a control interval, the record is contained on more than one control interval. This option allows VSAM to select a control interval size that is optimum for the DASD.
Speed Select this option to prevent preformatting of the control areas of the data component during loading (creation) of a data set.
Table 3. IDCAMS DEFINE CLUSTER options that are available in the Dataset Define Cluster dialog box of the Storage Toolkit. Part 3 of 3, (optional) Index component options
Option Description
Fully Qualified Name Type the fully-qualified name of the index component.
Fully Qualified Model Type the fully-qualified name of the index component that you want to use as a model.
Space Units Select the unit of space that you want to allocate in the volume. Options include cylinders, kilobytes, megabytes, records, or tracks. Then specify a corresponding value for the unit that you selected. The Primary value that you specify allocates the initial amount of space to the data component. The Secondary value that you specify allocates an amount of space for each time the index component extends.
Volser(s) Specifies the volumes on which a component is to have space. The maximum number of VOLSERs is 59. Choose one of the following values in the list:
  • The serial number of an eligible direct access volume on which a new component is to be located

    OR

  • The serial number of a direct access volume on which an old component is located. If you choose an old component for Volser, the component must be on the specified volume for allocation to take place. If you do specify a value for Volser, the system allocates new components to any eligible direct access volume.
Control interval size The size of the control interval for the component.
Share Options These settings determine how a component or cluster can be shared among users. To ensure integrity, you should be sure that share options specified at the DATA and INDEX levels are the same.
  • Cross Region: Specifies the amount of sharing allowed among regions within the same system.
  • Cross System: Specifies the amount of sharing allowed among systems. Job steps of two or more operating systems can gain access to the same VSAM data set regardless of the disposition indicated the DD statement for the data set in each step.
For information regarding the options, see the description of the IDCAMS DEFINE CLUSTER command consult DFSMS Access Method Services for Catalogs. A general link to this documentation is provided in Table 1.
Reuse Select this option to enable the component to be opened repeatedly as a reusable cluster.
Parent topic: Data set actions in the Storage Toolkit