Utility Functions › VSAM Utility › Define Alternate Index File › Field Descriptions

Field Descriptions

Component DSNs:

AIX data

Update the DSN of the data component of the Alternate Index file being defined. The DSN defaults to the cluster name of the Alternate Index with '.DATA' appended.

AIX index

Update the DSN of the index component of the Alternate Index file being defined. The DSN defaults to the cluster name of the Alternate Index with '.INDEX' appended.

Base cluster

Type the DSN of the base cluster to which this Alternate Index file is related. The base cluster must be a KSDS or ESDS VSAM file.

AIX Allocation:

Volume

Type the Volume serial of the volumes that contain the data and index components of the Alternate Index file being defined.

If either the data or index components require multiple volumes, type the first volume in this field and set the Multiple Volumes? option field to Y. This selection requests a screen where you can type the remaining volumes.

CI size (opt)

Type a control interval size for the data component and for the index component of the Alternate Index. If left blank, VSAM calculates the optimum control interval size.

Unit

Specify the space allocation unit for the VSAM file component. The primary and secondary allocations will be in the specified units.

Type the first position of one of the valid values. The rest of the Allocation Unit appears in the field.

T–TRKS

Tracks

C–CYLS

Cylinders

R–RECS

Records

K–K

KB (Kilobytes)

M–M

MB (Megabytes)

Primary

Type the primary allocation amount for the VSAM file component. The amount of space allocated in the primary allocation is the specified number of tracks, cylinders, records, KB, or MB depending on the allocation unit

Secondary

Type the secondary allocation amount for the VSAM file component. The amount of space allocated in each secondary allocation is the specified number of tracks, cylinders, records, KB, or MB depending on the allocation unit.

AIX key pos

Type the position of the alternate key field within the base cluster. The Alternate Key Position value is specified as a position and not as a displacement. For example, if the alternate key field begins in the first position of the base cluster's data component, type a value of 1.

AIX key len

Type the length of the alternate key field within the base cluster.

Avg AIX rec size

Type the average record sizes for the alternate index record or erase the field to receive the VSAM default value of 4086.

Max AIX rec size

Type the maximum record size for the alternate index records erase the field to receive the VSAM default value of 32600.

Each alternate index record contains 5 bytes of VSAM control information followed by the alternate key value, and by a table of pointers to the records in the base cluster that contain that alternate key value. Therefore, the length of each alternate record can be calculated as:

    5 + AIXKL + (n * BASEKL)

where:

• AIXKL is the alternate index key length, 'n' is the number of base cluster records containing the alternate key value
• BASEKL is the key length of the base cluster (or 4 for ESDS base clusters)

Expiration Date

To allow the Alternate Index VSAM file to be deleted after a certain date, type an Expiration Date in CCYYMMDD format.

Owner ID

This optional field can be used to specify an owner to associated with the VSAM file that is being allocated. If the Owner ID is not specified, the TSO User ID is defined as the owner.

Percent Free CI & CA

CI – Type the amount of empty space to allocate in each Control Interval when the file is initially loaded. The free space lets records be inserted or expanded within a Control Interval before requiring a Control Interval split.

CA – Type the percentage of control intervals to be left unused in each Control Area as the file is initially loaded. The use of Control Area free space lets some Control Interval splits occur before requiring a Control Area split.

Share options

Cross-Region – Type a value from 1 to 4 to indicate how the file can be shared among regions within the same system or within multiple systems using GRS (Global Resource Serialization). The meaning of each value is as follows:

1. The data set can be opened for read processing by an unlimited number of users, but only one user can access the data set when that user is doing read and write processing.
2. Only one user at a time can open the data set for read and write processing, but any number of users can also be accessing for read processing.
3. Any number of users can fully share the data set.
4. Any number of users can fully share the data set. For each PUT request, VSAM immediately updates the data set. For each GET request, all input buffers are refreshed.

Cross System – Type a value of 3 or 4 to indicate how the file can be shared among systems. The meaning of each value is as follows:

Any number of users can fully share the data set.

Any number of users can fully share the data set. For each PUT request, VSAM immediately updates the data set. For each GET request, all input buffers are refreshed.

Buffer space

Optional field used to specify the minimum buffer space allocation when this VSAM Alternate Index file is accessed.

If this parameter is not specified, VSAM uses the default of two times the data CISIZE plus the index CISIZE (if file is indexed).

Options:

Multiple volumes?

When the data or index component of the VSAM file requires multiple volumes, set the Multiple Volumes? field to Y to request a screen where you can type the volume serial for additional volumes.

AIX in sync with base?

Type Y for Yes or N for No to designate whether the alternate index is created with the UPGRADE parameter indicating that the alternate index be kept in sync with the base cluster. With the UPGRADE parameter, the alternate index is updated to reflect changes as they occur to the base cluster.

Unique key in base?

Type Y for Yes or N for No to indicate whether the alternate index is created with the UNIQUEKEY parameter indicating that each alternate index record points to only one data record in the base cluster.

Load Restartable?

Type Y for the Load Restartable? option to request that the VSAM component definition use the RECOVERY parameter causing the data component to be preformatted previous to the initial load. Using this option causes the initial load to take longer, but loads that do not complete successfully can be restarted.

Type N for the Load Restartable? option to request that the VSAM component definition use the SPEED parameter causing the data component to not be preformatted previous to the initial load.

Erase on delete?

Type Y for the Erase on Delete? option to request that the VSAM component definition use the ERASE parameter to overwrite all components of the file with binary zeros when the VSAM file is deleted from the catalog.

Type N to define the VSAM component with the NOERASE parameter.

Write check?

Type Y for the Write check? option to request that the VSAM component definition use the WRITECHECK parameter requesting validation of each write to the VSAM file by a read without data transfer.

Type N to define the VSAM component with the NOWRITECHECK parameter.

Replicate index?

Type Y for the Replicate Index? option to request that the VSAM component definition use the REPLICATE parameter requesting that the index records be replicated on a track as many times as will fit.

Type N to define the VSAM component using the NOREPLICATE parameter. Use of the REPLICATE parameter improves the time required to access index records, but usually causes the index to require more space.

SMS – Data Class

Type the one-to-eight position name of the SMS Data Class to use when allocating the Alternate Index VSAM file. The SMS Data Class can be used to control the attributes of the data set being allocated.