FORTRAN Reference Manual

Statements
FORTRAN Reference Manual—528615-001
7-73
OPEN Statement
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Improving program performance
If a file is a structured disk file (relative, entry-sequenced, or key-sequenced), your
FORTRAN program runs faster if you specify the following attributes in the file’s
OPEN statement. These attributes enable sequential block buffering:
ACCESS = 'SEQUENTIAL'
MODE = 'INPUT'
PROTECT = 'PROTECTED' or 'EXCLUSIVE'
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Spooler output with ENV OLD
By default, your program uses level-3 spooling if the file you write to is a spooler
collector. If you open a spooler collector for which you want to specify level-2 or
level-3 spooling parameters and your program does not specify ENV COMMON,
you must call the FORTRANSPOOLSTART routine after the OPEN statement and
before the first WRITE statement for the file. For more information about
FORTRANSPOOLSTART, see the FORTRANSPOOLSTART Routine on
page 15-16.
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Spooler output with ENV COMMON
By default, your program uses level-3 spooling if the file you write to is a spooler
collector. If you want to open a spooler collector and specify level-2 or level-3
spooling parameters, and your program specifies ENV COMMON, you must call
the FORTRAN_SPOOL_OPEN_ routine. FORTRAN_SPOOL_OPEN_ combines
the functionality of both the OPEN statement and the FORTRANSPOOLSTART
routine that you use in programs that do not specify ENV COMMON. For more
information about FORTRAN_SPOOL_OPEN_, see the
FORTRAN_SPOOL_OPEN_ Routine on page 15-11.
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FILE specifier
fn must be a valid file name. If fn is all blanks, or if you omit this specifier and you
do not supply a file name using a UNIT directive or ASSIGN command for the
unit, FORTRAN creates a temporary file, which is deleted if the number of
connections to the file goes to zero, or, if the file hasn’t been closed already, then
when your job ends. The temporary file is deleted regardless of the status specified
when you execute an OPEN or CLOSE statement.
If ENV COMMON is in effect, fn can reference a device on another node, even if
the device name on the node contains eight characters, as in the following:
OPEN (8, FILE = \NODENAM.$USERVOL.ASUBVOL.AFILE)
You can access a volume on another node, even if the volume name contains an
eight-character volume name, only if the node that you access is running a D-
series system. If, when you run your program, \NODENAM is running a C-series
operating system, your request will fail, even if the node on which your program is
running is using a D-series system.
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Sharing access to unit 5 and unit 6