Datasets can be defined and managed by the user via three dataset control statements: ASSIGN, ACCESS, and RELEASE.
• ASSIGN creates a dataset on mass storage and assigns dataset characteristics for tape and disk.
• ACCESS (defined in part 2, section 4) makes an existing disk or tape permanent dataset local to a job or can be used to create a dataset on magnetic tape1 ASSIGN assigns tape dataset
characteristics.
• RELEASE relinquishes access to the named dataset for the job.
ASSIGN - ASSIGN MASS STORAGE OR MAGNETIC TAPE DATASET CHARACTERISTICS The ASSIGN control statement creates a mass storage dataset and assigns dataset characteristics for tape and mass storage. If an ASSIGN is used for dataset creation, it must appear prior to the first reference to the dataset1 otherwise, the characteristics are defined at the first
reference. If an ASSIGN is used for a tape dataset, it must follow the tape ACCESS request. ASSIGNS is a system verb.
Format:
ASSIGN,DN=dn,S=size,BS=blk,DV=ldv,DT=dt,DF=df,
RDM,U,MR,LM=lm,Dc=dc,BFI=bfi,A=un.
Parameters are in keyword form. The only required parameter is DN.
DN=dn Local dataset name. 1-7 alphanumeric characters, the first of which is A-Z, $, %, or @1 remaining characters may also be numeric. ON is a required parameter.
§ ASSIGN does not create a dataset which the CFT 1.10 OPEN statement recognizes as existing.
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s=size
dynamically allocated as needed. This parameter applies to mass storage datasets only and is ignored when used for magnetic tape datasets.
Buffer size. Number of IOOOa-word blocks to be reserved for user buffer. The default number of blocks is set by an installation parameter. BS generates an error if the U parameter is specified (indicating unblocked dataset structure) •
CB Character blocked. End-of-record RCWs are converted to line feeds. This is the default.
TR Transparent. End-of-record RCWs are not converted to line feeds. The user is responsible for
inserting line feeds.
Random dataset. If the RDM parameter is present, the dataset is to be accessed randomly. If the RDM parameter
is not specified, the dataset is accessed sequentially.
This parameter applies to mass storage datasets only and is invalid for magnetic tape datasets.
Unblocked dataset structure. If the U parameter is
present, the dataset is not in COS-defined blocked format.
If the U parameter is absent, the dataset is a COS blocked dataset. (See part 1, section 2 for information on
unblocked dataset format.) This parameter is invalid for interchange format tape datasets.
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MR
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LM=lm
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DC=da
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BFI=bfi
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Memory resident dataset. If this parameter is present, the system I/O routines write the buffers to the disk only if they become full. If the MR parameter is absent, the dataset is not a memory resident dataset. MR generates an error if the U parameter is specified. This parameter applies to mass storage datasets only and is invalid for magnetic tape datasets.
Maximum size limit for this dataset. lm specifies a decimal count of 512-word blocks. The job step will be aborted if this size is exceeded. The default and maximum dataset size limits are set by an installation parameter.
This parameter applies to mass storage datasets only and is ignored for magnetic tape datasets.
Disposition code. Disposition to be made of the dataset at job termination. This parameter applies to mass storage datasets only and is ignored for tape datasets. The default is SC.
da is a 2-character alpha code describing the destination of the dataset as follows:
IN The dataset is placed in the input queue of the default destination station.
ST Stage to mainframe. Dataset is made permanent at the mainframe of job origin.
SC Scratch dataset. Dataset is deleted.
PR Print dataset. Dataset is printed on printer at the mainframe of job origin.
PU Punch dataset. Dataset is punched on any card punch available at the mainframe of job origin.
PT Plot dataset. Dataset is plotted on any available plotter at the mainframe of job origin.
MT Magnetic tape. Dataset is written on magnetic tape at the mainframe of job origin.
Blank field initiation. Octal representation of ASCII code which indicates the beginning of a sequence of blanks.
BFI=OFF means that blank compression is inhibited. The default code is 338 (ASCII ESC code) but may be changed by an installation parameter.
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A=un Unit name. Unit names allow the user to refer to a dataset from a FORTRAN program. Each unit name is 4 characters in the form FTxx, where xx is the unit number specified. The unit number is an integer value in the range 0-102.
However, because unit numbers 100, 101, and 102 are
reserved for system use, a user may designate unit numbers 0-99.
Use of this parameter associates the designated unit with the dataset specified by the DN parameter. At job
initiation, unit FTOS is associated with dataset $IN and unit FT06 is associated with dataset $OUT. Unit names should not be used as dataset names.
NOTE
If a dataset is used in place of a unit name or vice versa, FORTRAN '77 auxiliary statements
(that is, OPEN, CLOSE, and INQUIRE) may produce unpredictable results.
RELEASE - RELEASE DATASET
The RELEASE control statement relinquishes access to the named data sets for the job. If a dataset is not permanent and its disposition code is SC (scratch), the mass storage assigned to the dataset is released to the system. If the dataset is to be staged, the dataset is entered in the output queue for staging to the default destination station. An
end-of-data is written to a permanent dataset when it is released if the dataset is blocked sequential and the previous operation was a write.
Format:
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Parameters:
DN=dn· 1,
HOLD§
Name of dataset to be released. A maximum of eight datasets may be specified.
Hold generic device; do not return it to the system pool.
This parameter applies to magnetic tape datasets only and is ignored for mass storage datasets.
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