JCL Basics What is JCL? Job Entry Subsystem Job Processing JCL Statements JCL Parameters JOB Statement Job Statement Parameters for Job Positional Parameters ACCT NAME Keyword Parameters MSGLEVEL MSGCLASS TYPRUN PRTY CLASS RESTART REGION TIME NOTIFY EXEC Statement EXEC Statement Positional Parameters PGM PROC Keyword Parameters COND PARM ADDRSPC DD statement DD statement DD Parameters SPACE SYSIN VOL DCB SYSOUT DSN UNIT DISP |
DD statement • Used to describe data • Data includes dataset, instream data, etc. • The information given by DD statement includes dataset name, the residency of the dataset, DCB information, etc., • The DD statement consists of the characters // in columns 1 and 2 and four fields: name, operation (DD), parameter, and comments. • Do not code comments if the parameter field is blank. • A DD statement is required for each data set. • The maximum number of DD statements per job step is 3273, based on the number of single DD statements allowed for a TIOT (task input output table) control block size of 64K. • This limit can be different depending on the installation-defined TIOT size. The IBM-supplied default TIOT size is 32K. Concatenation of DD statements: • Two or more DD statements can be concatenated to a single ddname. • It is done by following the below mentioned rules: – Code the DD statements continuously in the JCL segment. – Specify the ddname only for the first DD statement. – Avoid coding the ddname for the remaining DD statements. • The datasets will be processed in the same order in which it is coded in the JCL (top – down). |
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