Datasets are defined and managed by the user through three dataset control statements: ASSIGN, ACCESS, and RELEASE.
• ASSIGN defines characteristics for datasets. ASSIGN also can be used to create a mass storage dataset.
• ACCESS (described 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 tape.
• RELEASE relinquishes access to the named dataset for the job.
ASSIGN - ASSIGN 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 before the first reference to the dataset; 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. ASSIGNt is a system verb.
Format:
ASSIGN,DN=dn,s=size,Bs=blk,DV=ldv,DT=dt,DF=df,
3
RDM,U,MR,LM=lm,DC=dc,BFI=bfi,A=un.
Parameters are in keyword form. The only required parameter is DN.
t ASSIGN does not create a dataset which the CFT OPEN statement recognizes as existing.
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DN=dn
s=size
Bs=blk
Dv=ldv
DT=dt
DF=df
Local dataset name. 1 through 7 alphanumeric characters, the first of which is A through Z, $, %, or @; remaining characters may also be numeric. DN is a required parameter.
Dataset size. Octal number of sectors (5l2-word blocks) to be reserved for the dataset. The mass storage space
reservation occurs during the first physical write to the dataset. If the dataset size is not given, the space for the dataset is dynamically allocated as needed. This
parameter applies to mass storage datasets only and ignored when used for magnetic tape datasets.
Buffer size. Number of 5l2-word blocks to be reserved for a 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).
Logical device on which the dataset begins. If a logical device name is not given, one is chosen by the system.
Consult the on-site analyst for possible logical device names. This parameter applies to mass storage datasets only and is ignored when used for magnetic tape datasets.
Device type. The allowable device types are CRT
(interactive) and MS (mass storage). MS is .the default.
This parameter is ignored when used for magnetic tape datasets.
Dataset format. This parameter is used only on output; it is valid only when DT=CRT. This parameter is ignored when used for magnetic tape datasets. Two formats are supported:
CB Character blocked. End-of-record RCWs are converted (normally to line feeds). This is the default.
TR Transparent. End-of-record RCWs are not converted.
The user is responsible for inserting line feeds.
RDM Random dataset. If the ROM parameter is present, the dataset is read and written randomly (that is, records may
be read or written out of sequence). If the RDM parameter is not specified, only sequential or FORTRAN direct access I/O is allowed on the datasets. This parameter applies to mass storage datasets only and is invalid for magnetic tape datasets.
U
MR
LM=lm
Dc~e
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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.
Memory-resident dataset. If this parameter is present, the system I/O routines write the buffers to mass storage 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 5l2-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 when it is released. This parameter applies to mass storage datasets only and is ignored for tape datasets.
The default is SC.
de
is a 2-character alphabetic code describing the destination of the dataset as follows:IN The dataset is placed in the input queue of the 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.
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BFI=bfi Blank field initiation. Octal representation of ASCII code indicating the beginning of a sequence of blanks. BFI=OFF means that blank compression is inhibited. The default code is 338 (ASCII ESC code) but can be changed by an installation parameter.
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 through 102. However, because unit numbers 100, 101, and 102 are
reserved for system use, a user may designate unit numbers
o
through 99.Use of this parameter associates the designated unit with the dataset specified by the DN parameter. At job
initiation, unit FT05 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 name is used in place of a unit name or vice versa, FORTRAN '77 auxiliary statements (that is, OPEN, CLOSE, and INQUIRE) produce unpredictable results.
RELEASE - RELEASE DATASET
The RELEASE control statement relinquishes access to the named datasets 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 destination station. An end-of-data record is written to a permanent dataset and an ADJUST is performed when it is released if the dataset is blocked sequential and the previous operation was a write.
Format:
Parameters:
DN=dn' 1.,
HOLD
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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.
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