2.5 The DD Control Card
The DD control card allows you to define single or multi-line 'datasets' for use by the various commands in the job stream. The syntax of the DD card is one of the following:
//ddname DD "single-line-constant"
“ “ *
“ “ *,EOF
“ “ *,EOF,Res=Disk
“ “ *,EOF,Res=Storage
'ddname' is the name the dataset is to be given. It must follow the general label naming convention, cannot be omitted and cannot appear more than once in the job stream. That is, datasets cannot be concatenated by means of several DD cards.
"single-line-constant" denotes a single-line dataset, whose value is that of the first (quoted) argument. The length of this argument must not exceed 255 bytes.
'*' denotes a multi-line dataset, whose successive lines immediately follow the DD card. Any number of lines can thus be included in a dataset, with a "/*" line indicating the end of the dataset. The JCL "DD DATA,DLM='xxxx'" is not implemented. Note that unlike JCL, CJLI does NOT end the dataset when a control card (i.e. one starting with "//") is encountered; the "/*" must always be specified.
'*,EOF' denotes a multi-line dataset, whose successive lines immediately follow the DD card and end at the end of the PHYSICAL job file. This option is used when transmitting "unknown" data in a dataset that could contain any kind of character string. Needless to say, there can be only one such dataset in the job file, and it must be the last dataset in the last job.
'Res=' indicates whether the dataset is to reside in storage ("Res=Storage") or on disk ("Res=Disk"). In some cases it may be necessary to keep a large dataset on disk to avoid running out of storage and to improve execution speed when a disk-file is to be generated anyway by the command using the dataset. The "Res=" keyword is therefore ignored on all datasets except the '*,EOF' one (if present), and causes a disk file to be generated with the remainder of the input deck. Please note that not all commands will support the "Res=Disk" option: commands which do not expect to receive a large dataset as input will usually expect to find it in storage and report an error when the "Res=Disk" option is used. For example, DISTRIBUTE fully supports "Res=Disk" while DELETE doesn't.
An invalid dataset declaration causes the job to be terminated by CJLI with the remaining jobs in the physical file still being executed.