Dataset - Rules & Types

 What is DATASET ?

Data is organized in various logical records and block structures is called datasets (rather than unstructured streams of bytes).

A dataset is a collection of logically related data records stored on one or a set of volumes.

The logical record is the basic unit of information used by a processing program.

A name with a single segment is called an unqualified name. A name with more than 1 segment is called a qualified name. Each segment of a qualified name is called a qualifier.

Conventions for creating datasets:-

1. A data set name can be one name segment or a series of joined name segments (qualifiers), separated by a period (.).
2. A data set name cannot be longer than 44 characters, out of that 22 variables can be there.
3. A segment cannot be longer than eight characters.
4. A data set name cannot contain two successive periods or end with a period.
5. The first segment character must be either a letter or one of the following three special characters: #, @, $.
6. The remaining seven characters in a segment can be letters, numbers, special characters (only #, @, or $).
7. A data set name cannot contain accented characters (à, é, è, and so on).

The following names are not valid data set names:-

• Name with a qualifier that is longer than eight characters (HLQ.ABCDEFGHI.XYZ).
• Name containing two successive periods (HLQ..ABC).
• Name that ends with a period (HLQ.ABC.).
• Name that contains a qualifier that does not start with an alphabetic or special character (HLQ.123.XYZ).

Types of Dataset:-

    1. NON-VSAM

    2. VSAM

        NON-VSAM:--

        --->    Physical Sequential (PS)

        --->    Partition Organized (PO)  

                  --->    Partitioned Dataset (PDS)

                  --->    Partition dataset Extended (PDSE)

        VSAM:--

        --->    key-sequenced data set (KSDS)

        --->    Entry-sequenced data set (ESDS)

        --->    Linear data set (LDS)

        --->    Relative record data set (RRDS)