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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.
2. DISP Parameter: “DISP” stands for Disposition, a keyword parameter used in JCL to describe a data sets 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.
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.
4. SPACE Parameter: The SPACE parameter indicates how much space is required to store a dataset on a Direct Access Storage Disk.
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.
1 What is the significance of using the “//” symbol in JCL?
It is an important symbol used in JCL statements since every JCL statement must begin with it. JCL statements must satisfy this rule in order to execute properly. Otherwise, the JCL statement will fail. During JCL execution, the system checks for the symbol (//) at the beginning of each statement. This prevents runtime exceptions.
1 How can we convert a FB (Fixed block) file to VB (Variable block) file using a sort program?
By using the FTOV option in SORT, you can convert a FB file to a VB file. Input records of fixed length are converted to output records of variable length using this parameter. VB files should have 4 extra bytes for RDW (Record Descriptor Word). Accordingly, the length of the record in the VB file is the RDW (4 bytes) + the actual length of the record.
Here, SORTOUT1 is the VB output file.
If you input an 80-byte FB file, then the output will be an 84-byte VB file (4 bytes for RDW).