1.

What are different parameters for DD (Data Definition) statement?

Answer»

Some of the parameters for the DD statement are listed below. BASED on your needs, you can select one or more parameters separated by commas. 

1. DSN Parameter: It is used to specify the name of a newly created or existing dataset. There can be a total of 44 characters in the DSN value. The sub-names can be 1 to 8 characters in length, separated by periods.

Syntax:  

DSN=Physical Dataset Name

Here, 

  • The keyword DSN specifies DSN parameter.
  • Physical dataset name refers to the name of the newly created or existing dataset.

2. DISP Parameter: "DISP" stands for Disposition, a keyword parameter used in JCL to describe a data set's status to OS. Essentially, it indicates how the OS should handle the dataset after JOB/STEP termination. It contains three sub-parameters: status, normal and abnormal termination activities of the JOB.

Syntax: 

DISP=({status},{normal Disposition},{abnormal Disposition})

Here, 

  • The keyword DISP specifies the Disposition parameter.
  • Status can be NEW (specifies that the dataset is new), OLD (specifies that the dataset exists when the step begins.), MOD (EXTENDS the dataset if the dataset already exists or creates a new one if it is not existing.), or SHR (specifies that the dataset can be shared (read access) with other jobs).
  • The normal disposition specifies what is to be done with a dataset after a normal termination. It takes one of the values CATLG, UNCATLG, PASS, KEEP, or DELETE.
  • The abnoram disposition specifies what is to be done with a dataset after a normal termination. It takes one of the values CATLG, UNCATLG, KEEP, DELETE.

3. DCB Parameter: DCB (Data control block) parameter provides information about the physical characteristics of a dataset. For newly created datasets, this parameter is required.

Syntax: 

DCB=<List of parameters>

Here,

  • The keyword DCB specifies the data control block parameter.
  • List of parameters can be RECFM (specifies record format of the dataset), LRECL (defines the length of logical records), BLKSIZE (defines the size of a block of record), DSORG (specifies the organization of the data set as physical SEQUENTIAL (PS), partitioned (PO), or direct (DA)).

4. SPACE Parameter: The SPACE parameter indicates how much space is required to store a dataset on a Direct Access Storage Disk.

Syntax: 

SPACE=(Unit of Space,(Primary,Secondary,Directory),RLSE,CONTIG,ROUND)

Here,

  • The keyword DCB specifies the data control block parameter.
  • The unit of space is SPECIFIED in Tracks (TRK), Cylinders (CYL), block length (BLKLGTH), record length (RECLGTH).
  • Primary specifies the amount of primary space required in terms of the space unit (tracks/cylinders/number of data blocks)
  • Secondary specifies the secondary quantity of units if the primary is exceeded but ALLOCATED only when the dataset expands.
  • The directory specifies the number of directory blocks to be allocated.
  • RLSE specifies releasing the unused space requested.
  • CONTIG specifies to allocate contiguous primary space.
  • ROUND specifies allocation by block length rounded to integral cylinders.

5. SYSOUT Parameter: We have discussed so far the parameters of DD statements that correspond to data stored in datasets. According to the class specified, SYSOUT directs the data to the output device.

Syntax: 

SYSOUT=class


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