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JCL Notes
Order of Parameters
Lab submissions must have their keyword parameters specified in the following
order, to facilitate marking. (JES and MVS don't care about keyword
parameter order; the instructor does when he has to mark 60 assignments!)
Note! Not all of these parameters are necessarily present in your
particular job. When you do specify some of these parameters, specify them
in the following order. Don't specify things that don't apply to your job!
//jobname JOB acct,name,CLASS=,
MSGCLASS=,MSGLEVEL=,PRTY=,TYPRUN=
//stepname EXEC PGM=,PROC=,
COND=,PARM=,TIME=,REGION=
//dd.name DD *,SYSOUT=,SYSOUT=(class,,form),
BURST=,COPIES=,DEST=,FLASH=,HOLD=,OUTLIM=,
DSN=,DISP=,
UNIT=,VOL=SER=,LABEL=(,),
DCB=(DSORG=,LRECL=,BLKSIZE=,RECFM=),
SPACE=(,(,)),
Notes
 | Always document your "guesses" in your JCL. Explain what
you are guessing and how that affects your JCL coding. |
| Look up unfamiliar parameters in your text before you use them. Know
what you are saying before you say it. |
| Input datasets have their DCB information stored in their labels.
You don't need to code any DCB parameters in the JCL for input datasets. |
| IDCAMS REPRO creates its output dataset using the DCB of the input
dataset, unless you code JCL to adjust the output dataset DCB. (Many
times you do want a different BLKSIZE= for the output dataset.) Pay
attention to the efficient use of the output dataset medium and re-block
your output accordingly. |
| If you code a BLKSIZE=, also code RECFM=FB. (Don't code BLKSIZE= all
by itself.) |
| Instream data always has this data control block
format: DCB=(DSORG=PS,LRECL=80,BLKSIZE=80,RECFM=F) Be careful to
re-block the output when writing instream data to disks and tapes. |
| ANSI label tapes always need to be identified in the JCL as having ANSI
labels, even on input, even if catalogued. (The label is the first
thing on the tape - you have to know what kind of label it is to be able to
read it!) |
| Writing to tapes, you never need to allocate SPACE=; but, you must
maximize the output DCB block size to avoid wasting space and slowing down
the job. |
| Writing to disk, you need to allocate SPACE= (and possibly DCB=
parameters, if the program writing the dataset doesn't specify them already)
if this is a new dataset. If it is an existing
dataset, the existing dataset label has the SPACE= and DCB= information
already (see p.121). |
| When specified, the BLKSIZE= value and the first parameter of SPACE= are
the same number. (It should be set to the maximum number of bytes you
can write without going over the appropriate output block size.) The
actual number you must specify depends on the record length (LRECL=) of your
data and the maximum block size of your output medium. The maximum
block size is usually 4K; but, there are exceptions. |
| ANSI tapes have a maximum block size of 2K. |
| When you specify input libraries to search, allocate them as SHR, not OLD! |
| When calculating the number of tape drives needed for your job CLASS=,
remember that it is the maximum number needed simultaneously, in one
single step. It is not the sum of all the tape drives used. A
job may use ten tapes and still require only one tape drive, if the ten
tapes are used only one per step in ten job steps. |
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