JCL - Job Control Language
DEFINITION:
JCL
is an interface between application program and operating system
1.
JCL is an 80 byte record structure
2.
By using JCL we can execute or bypass any no of steps ion a
job
3.
By using JCL we can use any no of data sets required for job
execution
4.
By using JCL we can also define status of the used data sets
The 80 byte record structure is
as follo
JCL Statements:
In JCL we have 3 statements.
They are…..
1.
Job Statement
2.
EXEC Statement
3.
DD Statement
1.
JOB STATEMENT:
a)
Specifies the starting of the job
b)
We can write only one job statement in one JCL
c)
In job statement we have both positional and keyword
parameters
i.
Positional Parameters:
In
job statement we have two positional parameters. They are…..
a.
ACCOUNTING INFORMATION
b.
PROGRAMMER NAME
1)
These two are mainly used for the billing purpose to include
the bill amount and billers name
2)
These two are also used in job statement for writing job
related description
1.
Positional parameters always follow the order
2.
If any one of the above parameter is absent we have to
separate with ‘comma’(,)
3.
If two parameters are absent ignore the field
4.
Positional parameters in job statement are optional
ii.
Keyword Parameters:
The
list of keyword parameters existed in a job statement are as follows
1.
CLASS
2.
PRTY
3.
MSG CLASS
4.
MSG LEVEL
5.
TIME
6.
REGION
7.
RESTART
8.
ADDRSPC
9.
TYPRUN
10.
NOTIFY
1.
CLASS:
1.
It is mainly used for categorizing the input jobs
2.
Based on CLASS value we can create or bypass the steps
3.
Possible values are a-z, 0-9
4.
Syntax: CLASS = VALUE
CLASS
parameter is optional because by default the value is CLASS = A
2.
PRTY:
When
two jobs CLASS names are same based on given priority the is executed
The
priority value ranges from 0-15
Priority
is optional for individual jobs
3.
MSGCLASS:
It
is mainly used for routing the output messages of a job
Possible
values are a-z
MSGCLASS
is optional
Syntax: MSGCLASS = VALUE
4.
MSGLEVEL:
It is used to print the level of
output description
Syntax: MSGLEVEL = (N,M)
Where
N = JCL messages & M = Allocation messages
The
possible values for N are
a.
0 - it prints only job card
b.
1 - it prints user coded JCL and procedure
messages
c.
2 - it prints only the user coded JCL
messages
The possible values
for M are
a.
0 - if job terminated abnormally then only
it prints messages
b.
1 - irrespective of job execution it prints
the messages
MSGLEVEL
is optional because the default value is MSGLEVEL = (1,1)
5.
TIME:
1.
Time specifies the maximum amount of time required for job execution
2.
In time we have various values as follows………
i.
TIME = (M,S) M = Minutes , S = Seconds
ii.
TIME = MAXIMUM. It takes the
maximum time of a server
I.e.357912 minutes
approximately 8.25 months
iii.
TIME = NO LIMIT or 1440.It takes infinite
time for job execution. 1440 is logical value which specifies no limit
6.
REGION:
Specifies
maximum amount of memory require for job execution
Syntax:
K or where K = Kilobytes, M =
Megabytes
M
The Maximum memory
for REGION is 4M
7.
RESTART:
1.
Using RESTART parameter we can bypass any no of steps only from beginning
2.
Using RESTART we cant bypass the steps randomly
EX:
s1, s2, s3, s4, s5, s6 are the steps
RESTART s2
In
the above example execution start from step2 onwards
8. TYPRUN:
1. It
specifies the execution status of a job
2.
Using TYPRUN we can also check the JCL code i.e. Syntax check
3.
TYPRUN having different values as follows……
SYNTAX:
TYPRUN = SCAN – It checks only syntax
errors and wont execute the job
TYPRUN = COPY – It copies the use code
and JCL on to the spool
TYPRUN = HOLD – It checks only syntax
errors and execute the job
TYPRUN = HOLD – is default
9.
ADDRSPC:
a.
It specifies where the job is executing
b.
EX: ADDRSPC = VIRTUAL
Or
REAL
10.
NOTIFY:
a.
It notifies the execution status of the job to the specific
User ID or default login ID
b.
Syntax: NOTIFY =
&SYSUID OR
USER ID
c.
In job statement NOTIFY parameter is mandatory.
2.EXEC
STATEMENT:
EXEC
statement specifies starting of a step. Max 255 EXEC statements can be written
in one JCL
a.
Positional
Parameters:
1.
PGM - Specifies the program name or load module
2.
PROC – Specifies the procedure
Any one of the above parameters
is required for the job execution
b.
Keyword Parameters:
1.
TIME
2.
REGION
3.
PARM
4.
COND
1. PARM:
By
using PARM parameter we can pass max 100 characters of data to the program
PARM
is available character which contain both text & length fields
2.
COND:
By
using COND parameter we can execute or bypass any no of steps in a job
In
COND parameter it always take previous step return code only i.e. MAXCC
If
the given condition is satisfied it bypass the current step from execution if
not the current step is executed
COND
is opposite to the IF statement
Syntax: COND = (Status Code,Operands,Step
Name)
Example:
S1 MAXXCC = 4
S2 COND = (4,EQ)
S3
S4
S5
Because of given condition step
2 will be bypassed from execution.
In COND we have 2 special
values. They are……….
a.
COND = ONLY – If it is coded then the current step is
executed if and only if the previous step is abended
b.
COND = EVEN – If it is coded then irrespective of previous
step execution it process the current step
3.
DD STATEMENT:
DD
statement specifies the data sets using in a JCL
MAX
3273 DD statements can be written in one JCL
1. Positional Parameters:
a.
* (ALL) – It is used in control statement and also used in
various DD statements
EX: //SYSIN DD *
b.
Dummy – it is mainly used to bypass the input data
EX: //SYSIN DD DUMMY
c.
Data – It is mainly used to pass the JCL lines
EX: //SYSIN DD DATA
2. Keyword Parameters:
a.
DSN
b.
DISP
c.
SPACE
d.
DCB
e.
VOL=SER
f.
UNIT
a. DSN
(Data Set Name):
The
max length of DSN is 44 characters and for every 8 characters there will be a
qualifier and max 5 qualifiers are allowed
1st
qualifier should be USER ID. Possible values are a-z, 0-9, national characters
like #, @, $.
b. DISP
(Disposition):
Used to specify status for the
data sets
Syntax: (Status,Normal
Disposition,Abnormal Disposition)
c.
SPACE:
=
(SPACE UNIT,(PRIMARY,SECONDARY,DIRECTORY BLOCK),RLSE)
Directory Block is required only
for PDS. For PS its ‘0’.
RLSE (RELEASE) – It releases the unused
secondary quantity from the resource
d. DCB
(Data Control Block) – It specifies attributes of a data set
Syntax: DCB = (RECFM = FB,LRECL =
VALUE,BLKSIZE = Multiples of LRECL only)
RECFM :
specifies
record format
LRECL :
Logical
Record Length
BLKSIZE :
Block Size must be multiples of LRECL only
e. VOL
= SER (VOLUME SERIAL) – Specifies the name of volume in DASD
EX: VOL = SER = DEVMA0
f. UNIT
– Specifies
the device type
EX:
UNIT = 3390
3390: Specifies a logical
value for device type
SPECIAL
DD STATEMENTS:
1. SYSOUT – Specifies the output
of JCl
2. SYSPRINT – Used to Print the
program messages
3. SYSIN – Used to accept the
input data
4. STEPLIB – Used to include user
defined libraries
5. JOBLIB – It is also used to
include user defined libraries
6. JCLLIB – It is mainly used to
call or invoke catalog procedures
UTILITIES
Ø Utilities are IBM
supplied programs which are already coded, compiled and executed to perform a specific functionality
Ø All utilities are
pre-defined programs
Ø Utilities are mainly
divided into two types. They are…..
1.
Data Set Utilities
2.
System Utilities
Ø The list of utilities
available in JCL are as follows……
1.
IEBCOPY
2.
IEBCOMPR
3.
IEBGENER
4.
IEBEDIT
5.
IEBUPDTE
6.
IEBPTPCH
7.
IEHLIST
8.
IEHPROGM
9.
IEFBR14
10.
IDCAMS
11.
ICEMAN
12.
SORT
Ø All data set
utilities always start with prefix IEB
Ø All system utilities
always start with prefix IEH
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