The DD name used in the program must match the DDname in the DD statement. The DD statement in the task contains the real/full name of the record. DD names may not be unique among the different steps and must be unique in the particular step. The maximum number of DD statements per task step is 3273. Is there a limit of 3273 DD statements for a JCL or for each EXEC step of a JCL? The DD statement contains the dataset and its physical properties. Each EXEC statement can have the appropriate DD statements used in the application program or utility. Do not encode other statements between concatenated DD statements Do not encode other types of statements between two or more Concatenated Data Definition (DD) statements. (Comments are the only exception; You can encode them between DD statements.) For example, do not encode a SET statement as follows: The 3273 is based on individual DD statements allowed for a Task Input Output Table (TIOT) control block size of 64 KB. The number of DD statements may vary from system to system depending on the size of the TIOT control block. DD is short for Data Definition.
The definition of file-related details is mentioned here, such as input and output resources, file access, disk space, and file-related volume are also listed here. It must follow the EXEC statement after at least one space. An `EXEC` statement can contain multiple DD statements. Place DD statements that replace, replace, or add parameters immediately after the EXEC statement that calls the procedure. Place the parent and cancel DD statements first, followed by any DD statements you add. The final steps of the call are all DD* or DD DATA statements with their in-stream data. References to concatenated records When you make an inverse reference to a concatenation (with *.), the system receives only information from the first record, which is defined in the order of the DD statements. The maximum number of 255 steps can be present in a task. Each step can contain 3273 DD instructions.
From this statement we can understand that we can have 255* 3273 DD instructions in a single job. Previous JCL Instructions Next There are 3 important instructions in a JCL. This is – JOB StatementEXEC StatementDD Statement JOB This is the first instruction in a JCL. In the JOB statement, you must specify the JCL name, accounting information, class, msgclass, msglevel, and other parameters. We will cover all the parameters in detail as we continue in this tutorial. Example job statement //COPYCURR JOB (456),`TUTORIALBRAIN`, // CLASS=A,MSGCLASS=A,MSGLEVEL=(1,1), // NOTIFY=&SYSUID EXEC Statement This is short for EXECUTION. The EXEC statement marks the beginning of a step in a JCL or procedure. The EXEC statement contains the program, utilities, and procedures in which we use it to perform a step in a JCL. JCL allows a maximum of 255 steps, which means that a JCL can have a maximum of 255 `EXEC` statements.
Note: The name of the step in the `EXEC` statement is optional, but if the name of the step is omitted, no reference can be made to this step. Therefore, it is always advisable to specify the name of the step in the `EXEC` statement. It is best to specify a descriptive name of the stage name, and the stage name can be a maximum of 8 characters. Follow @tutorial_brain example of an EXEC statement //COPYDATA EXEC PGM=IEBGENER DD statement DD is the abbreviation for data definition. The definition of file-related details is mentioned here, such as input and output resources, file access, disk space, and file-related volume are also listed here. It must follow the EXEC statement after at least one space. An `EXEC` statement can contain multiple DD statements.– Describes the record or I/O resources required by the program– Source of the input and where the output is to be kept.– All DD instructions for a single task must follow the EXEC statement.– The DD name must be 1 to 8 characters long (alphanumeric or national characters allowed)The program must be located in one of the system library-libraryPrivate library – JOBLIB or STEPLIB are included in the DD statement for using a private libraryTemporary library – it is used in a program. For example, step 1 creates a temporary library so that step 3 can use it later. You can place the loading module in a temporary library until it is fully tested.
Example of DD statements //SYSPRINT DD SYSOUT=* //SYSOUT DD SYSOUT=* //SYSDUMP DD SYSOUT=* //SYSUT1 DD DSN=MATEKS. ROTATION. WEEK(-1),DISP=SHR //SYSUT2 DD DSN=MATEKS. TEST. PS4, // DISP=(NEW,CATLG,DELETE), // SPACE=(TRK,(1,2),RLSE), // UNIT=SYSDA, // DCB=(DSORG=PS,RECFM=FB,LRECL=80,BLKSIZE=800) //SYSIN DD DUMMY DDNAME specifies a name for the DD statement. The DD name is optional. It starts in column 3 and should end after the DD name at or before the task field in column 10DD – starts with 12 to 15 columns. DSN is a keyword parameter.
The physical name of the input or output file is provided hereLocation parameters are parameters that must always follow a certain orderKey parameters are parameters that do not follow a specific orderUnit and DISP parameters are providedOther spatial parameters are also provided in the DD statement. Previous Next Facebook Twitter Google-plus To replace multiple DD statements in a procedure, place the parent DD statements in the same order as the DD statements replaced in the procedure. Here is an example that uses DD statements with various parameters described above: If there are no DD statements between the direct reference and the concatenation, the remaining records of the concatenation are added to the first record of the concatenation. The following example illustrates this. 6.Position in the JCL Most DD statements define the records to be used in a task step, in a cataloged procedure step, or in an integrated procedure step. These are displayed after the EXEC statement in the step. Some DD statements define records for the task, for example.B. the JOBLIB DD declaration; These are displayed after the JOB statement and before the first EXEC statement. Encoding a concatenation To concatenate records, omit the ddnames from all DD statements except the first one in the sequence. Records are processed in the same order as the DD statements that define them.
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