Each numbered JCL statement in the previous example is described as follows:

1. The JOB statement specifies the beginning of a job and assigns a job name.
2. The EXEC statement specifies the beginning of a job step and identifies the assembler.
3. The PARM parameter specifies options for the assembler.
4. The SYSLIB DD statement specifies the macro library concatenation.
5. The SYSLIN DD statement specifies the data set that will contain the object module (ISGECMON). The partitioned data set USERID.MY.OBJ must contain the assembled member ISGECMON when this job ends.
6. The DCB (data set control block) specifies the DCB options.
7. The SYSIN DD statement specifies the data set that contains the source code.