Interested to Buy Any Domain ? << Click Here >> for more details...
Describe the DD statement, its meaning, syntax and keywords?
- 2 Answers
- 9295 Views
- I also Faced
- E-Mail Answers
Answer Posted / sunitha
Ans: The DD statement links the external dataset to the
ddname coded within the executing program. It links the
files within the program code to the filenames known to the
MVS Operating system. The syntax is:
//DDANAME DD DSN=NAME,
// DISP=(NEW,CATLG,DELETE),
// DCB=(DSORG=PS,RECFM=FB,LRECL=80,BLKSIZE=800),
// SPACE=(CYL,(20,5),RLSE),
// UNIT=SYSDA
DSN- Name of the dataset- separated by periods, each name 1
to 8 characters, total 44 chars including periods.
DISP- It specifies the disposition of the dataset.
DISP=(status,normal-disposition,abnormal-disposition)
Status – The statuses NEW,MOD,OLD,SHR are the status of the
dataset at the beginning of the step.
NEW is given to create a new dataset. It is the default if
anything is not coded.
OLD designates an existing dataset with exclusive control.
SHR designates an existing dataset without exclusive
control.
MOD is used to extend the dataset if it exists or to create
a new one if it does not exist.
Normal-disposition- It directs the system on the
disposition of the data set (pass, keep, catlg, uncatlg,
delete) when the step ends normally.
Abnormal-disposition- It directs the system on the
disposition of the data set (keep, catlg, uncatlg, delete)
when the step ends abnormally.
DCB- Physical characteristics of a Data Set are described
by DCB Parameters. These parameters must be coded for newly
created data set as well as for existing Datasets.
• LRECL=n (VALUE IN BYTES)
• RECFM=(F/FB/V/VB/U)
• BLKSIZE= multiple of LRECL
• DSORG=(PS/PO/DA)
PO: specifies a partitioned Organization, DA: specifies a
direct organization.
SPACE=(space units,
(primary,secondary,dir),RLSE,CONTIG,MXIG,ROUND)
space unit - TRK(tracks)/CYL(cylinders)/BLOCKSIZE in bytes.
In our above example it allocates 20 cycles primary and if
required allocates 5 secondary cycles.
RLSE- Request to release the space that is primarily
allocated if unused.
CONTIG- Request for contiguous space.
MXIG- Request for large area of contiguous space.
ROUND- Request for entire cylinder for storage of dataset.
UNIT parameter indicates the information about input or
output device that will be used
by the dataset. It specifies a group name, device type, or
device number that identifies the
device where the file resides. The Format of the UNIT
parameter is UNIT= groupname/
device-type/device number.
VOL parameter is primarily used for tapes. A volume is the
portion of the storage device served by one read/write
mechanism. To request specific volumes, we code
VOL=SER=volume for one volume or VOL=SER=(volume, volume…)
for multiple volumes. Volume serial numbers are one to six
characters.
SYSOUT parameter is used to route the output to a device.
// DDNAME DD SYSOUT=CLASS
| Is This Answer Correct ? | 6 Yes | 1 No |
Post New Answer View All Answers
What is the function of the dd dcb keyword?
how you will the direct the data to spool using sysout option?
what is JCL?
How does jcl act on code(if you take a cobol program)?
Is their any limit for data sets?
What is the purpose of the dd keylen parameter?
What are the difference between jcl and jes?
Explain the function of dd name parameter with a 2 part structure; audit.report?
what is DD statement is used in JCL?
I HAVE A VB BLOCK WHICH IS USED AS INPUT IN COBOL CONATINING SOME RECORDS CAN I CHANGE THE FILE FROM VB TO FB?
which utility is used a dummy utility?
How to execute 2nd and 4th steps among 5 steps in jcl proc?
How to pass the parameter in parm using linkage section ? (syntax)?
Where can program checkpoints be stored for use in a restart?
Is their any set of rules for dd? Explain.
