Describe the DD statement, its meaning, syntax and keywords?
Answers were Sorted based on User's Feedback
Answer / 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 |
Answer / guest
The DD statement links the external dataset name (DSN) to
the DDNAME coded within the executing program. It links the
file names within the program code to the file names know to
the MVS operating system. The syntax is // ddname DD
DSN=dataset name. Other keywords after DSN are DISP, DCB,
SPACE, etc.
| Is This Answer Correct ? | 3 Yes | 0 No |
how to run batch program without jcl?
What is GDG?
I want to JCL sort for Non-COMP and COMP-3 fields SORT FIELDS=(1,5,A,6,11,A,12,11,A,19,1,A,20,1,A),FORMAT=BI,EQUALS Length of comp bytes is 11 bytes which start at 6byte and 12 byte considering 11 bytes in comp-3 is 6 bytes. Can anyone tell if the above sort work SORT FIELDS=(1,5,A,6,6,A,12,6,A,19,1,A,20,1,A),FORMAT=BI,EQUALS does not works OK
Does jcl support automatic restart?
What is JOBLIB ?
how to identify the file used in the JCL is an VSAM file. Just seeing the JCL code how can we track the file as VSAM file?
In a JCL if previous steps return code is greater than 0 or 4 then the next step will not execute. But the job will be successfull with the maximum return code. How can we reset this maximum return code to '0' regardless of return codes of any steps?
How to execute 300 steps in a Job?
What is the purpose of disp parameter?
How does jcl act on a cobol code?
What u mean by include statement in JCL ?
diff bw SB37,SD37,SE37 ?( bcz these 3 belongs Space related abends only)