This can be done by using Sort. 

1) If the first duplicate is to be kept, we use SUM 
FIELDS=NONE

2) If none of the duplicates are to be kept, using SYNCTOOL 
or ICETOOL, use the NODUPS option.

//STEP10  EXEC PGM=SORT,REGION=1024K              
//SYSOUT    DD SYSOUT=*                 
//SORTIN    DD DSN=...,DISP=SHR              
//SORTOUT   DD DSN=...
//SYSIN    DD * 
      SORT FIELDS=copy 
      SUM FIELDS=NONE 
/* 
//

Joblib is a default load library for all the jobsteps

JOBLIB DD statement specifies the private library that the
system needs to search to obtain the program named in each
of the EXEC statements PGM parameters. Only if the program
is not found in the private, the system searches in the
system libraries.

Jcllib is the loadlib that contains cataloged procedures

JCLLIB statement species the private library that the system
needs to search to obtain
(a) the procedures (PROCS) named in the EXEC statement
(b) the Groups of JCL statements (called INCLUDE groups)
named on any INCLUDE statements

JCLLIB is used with either OS/390 or MVS/ESA Version 4 or 
higher JES2 or JES3 systems, to identify a private library 
or a system library from which INCLUDE groups and JCL 
procedures are to be retrieved.  The order in which the 
library names appear on the JCLLIB statement is the order 
in which they are searched for any JCL procedures (PROCs) 
and INCLUDE  groups referenced by this job.  

The JOBLIB DD statement is used to identify a program 
library to search first when attempting to locate programs 
executed during the job's life.  The JOBLIB must be placed 
after the JOB statement and before the first EXEC statement 
in the job.  More than one program library can be 
concatenated after the first one on a JOBLIB.

The DUMMY statement will allow a Jcl program to run if a
data set does not exist.

Following example:
//JOB1 JOB NOTIFY=&SYSUT1
//STEP1 EXEC PGM=IEBGENER
//DD1 DD DSN=IASM12.CLASS.PS1,DISP=SHR
//DD2 DD DSN=ISAM12.CLASS.PS2,DISP=SHR
//SYSIN DD DUMMY
//*Here statements tells about no input data.

Correct me if i'm wrong...... okai

dummy statement is used to suppressed command processing.

The DUMMY parameter specifies that no device is to be 
allocated to this DD statement and that no disposition 
processing or I/O is to be
done.  
One use of the DUMMY parameter is in testing a program.  
When testing is finished and you want input or output 
operations performed on the data set, replace the DD DUMMY 
statement with a DD statement that fully defines the data 
set.

Specifies no space allocation & no disposition processing

i think for the jcl ,we should have to give input in sysin 
dd ststement.if we dont give any input then by default we r 
giving this as an input. Becos they need a kind of input 
from that place. plz give suggesion for my answer.....

The use a a DD statement with a DUMMY parameter will allow 
a program to run if a data set does not exist. In the cobol 
program the OPEN will be successful, the first READ will 
return an End-of-File return code and the close will be 
successful.

//jobname positional parms,keyword parms,.... Restart=step3
//..
//..
//..
//step3 exec=xxxx 
//...
//step4 exec=yyyy,cond=(0,eq,step3)
//..
//step5 exec=zzzz

You can Use RESTART in job cards.
RESTART=JOBSTEPNAME.PROCSTEPNAME
Thanks

Sorry,my previous solution was wrong.Infact it is correct 
if you don't want to skip step 4th step

The correct solution for this is
to use COND paramater. 

The below given code provides the exact solution,

//STEP001 EXEC PGM=IEBEDIT
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=XXX.GENERAL.STUDY(TEST001),DISP=SHR
//SYSUT2   DD SYSOUT=(A,INTRDR)
//SYSIN    DD  *
 EDIT TYPE=EXCLUDE,STEPNAME=(STEP003,STEP005)
/*

This jcl is the correct answer, this is used to run a batch 
job in production environment.
*** if the JCL will run step3 and step5 condcode is 0
     while step4 condcode is flush means it will not run.

//jobname  jobcardxx
//         xxxxx
//         xxxxx
//         xxxxx
//..
//..
//step3 exec pgm=xxx,cond=(4,lt)
//....
//....
//step4 exec pgm=xxx,cond=(0,le)
//....
//....
//step5 exec pgm=xxx,cond=(4,lt)
//....
//....


RUDOLF M. AQUINO
SYSTEM PROGRAMMER(MAINFRAME)
UNITED COCONUT PLANTERS BANK
MAKATI CITY