What is record size in VSAM?

The record length is a value from 1 to 32,767.

How do you calculate record size for alternate index?

Use the following formulas to determine the average size of the alternate index record when the alternate index supports ESDS or KSDS. ESDS: RECSZ= 5 + AIXKL + (n x 4)…Calculating Record Size

  1. AIXKL is the alternate-key length.
  2. BCKL is the base cluster’s prime-key length.
  3. n=1 when the UNIQUEKEY parameter is specified.

How do you populate an alternate index in VSAM?

To use an alternate index, do these steps:

  1. Define the alternate index by using the DEFINE ALTERNATEINDEX command.
  2. Relate the alternate index to the base cluster (the data set to which the alternate index gives you access) by using the DEFINE PATH command.
  3. Load the VSAM indexed data set.

What is alternate key in VSAM?

In addition to the primary key, you can code one or more alternate keys for a VSAM KSDS file. By using alternate keys, you can access an indexed file to read records in some sequence other than the prime-key sequence. Alternate keys do not need to be unique.

What is free space in VSAM?

FREESPACE. Freespace specifies the percentage of free space to reserve for the control intervals (CI) and control areas (CA) of the data component. The default value of this parameter is zero percentage.

What is Esds in VSAM?

ESDS is known as Entry Sequenced Data Set. An entry-sequenced data set behaves like sequential file organization with some more features included. We can access the records directly and for safety purpose we can use passwords also. We must code NONINDEXED inside the DEFINE CLUSTER command for ESDS datasets.

What is a spanned record in VSAM?

Sometimes a record is larger than the control interval size used for a particular data set. In VSAM, you do not need to break apart or reformat such records because you can specify spanned records when you define a data set. The SPANNED parameter permits a record to extend across or span control interval boundaries.

How does VSAM calculate free space?

You can calculate space for the data component as follows:

  1. Number of bytes of free space (20% × 1024) = 204 (round down)
  2. Number of loaded records per control interval (1024–10–204)/200 = 4.
  3. Number of physical blocks per track = 33.
  4. Number of control intervals per track = 33.

What is Listcat in VSAM?

LISTCAT command in VSAM is used to view the properties of VSAM file like volume details, space details, path details, and catalog details. LISTCAT can list many properties like cluster, data, index, spae details, history, volume and much more.

Can we delete record from Esds file?

Records can never be deleted from an ESDS. To delete a single record in a KSDS or RRDS, use one of these three methods: Retrieve it for update with a READ UPDATE command, and then issue a DELETE command without specifying the RIDFLD option. Issue a DELETE command specifying the RIDFLD option.

How much free space does an ESDS will occupy?

A standard RBA is an unsigned 32 bit number. The use of a 32 bit RBA means that a standard ESDS cannot contain more than 4 GB of data.

What is spanned record?

A spanned record is a variable-length record in which the length of the record can exceed the size of a block. If it does, the record is divided into segments and accommodated in two or more consecutive blocks.