COND parameter is very important to control job steps in JCL. The COND controls flow of steps. You can control the steps execution in the JCL, in the in stream procedure, and in the cataloged procedure.
You can control execution of any step you want in JCL. This is advanced to COND by mixing of both if-else-endif.
//Myjob JOB (Acct),'me', CLASS=A,MSGCLASS=0, // MSGLEVEL=(1,1),NOTIFY=USERID //Step1 EXEC PROC1 //Cond1 IF RC=0 THEN //ESTEP1 EXEC PROC2 //Cond2 ELSE //ESTEP2 EXEC PROC3 // ENDIF //*