OPEN statement
The OPEN statement associates a file
with a data set. It merges attributes specified on the OPEN statement
with those specified on the DECLARE statement. It also completes
the specification of attributes for the file, if a complete set
of attributes has not been declared for the file being opened.
 .-,-----------------.
V |
>>-OPEN----| options-group |-+--;--| options-group: |----------->
.-STREAM-----. .-INPUT------.
>--FILE(file-reference)--+------------+--+------------+--------->
'-+--------+-' +-+--------+-+
'-RECORD-' | '-OUTPUT-' |
'-+--------+-'
'-UPDATE-'
.-BUFFERED-------.
.-SEQUENTIAL--+----------------+-.
| '-+------------+-' |
| '-UNBUFFERED-' |
>--+--------------------------------+--+-------+--+-------+----->
| .-UNBUFFERED---. | '-KEYED-' '-PRINT-'
'-DIRECT--+--------------+-------'
'-+----------+-'
'-BUFFERED-'
>--+-------------------+--+----------------------+-------------->
'-TITLE(expression)-' '-LINESIZE(expression)-'
>--+----------------------+------------------------------------><
'-PAGESIZE(expression)-'
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The options of the OPEN statement can appear in any order.
- FILE
- Specifies the name of the file that is associated with a data set.
- STREAM, RECORD,
- INPUT, OUTPUT, UPDATE,
- DIRECT,
SEQUENTIAL,
- BUFFERED, UNBUFFERED,
- KEYED,
and PRINT
- These options specify attributes that augment the attributes
specified in the file declaration. The same attributes need not
be listed in both OPEN and DECLARE statements for the same file.
For a list of attributes for record and stream input and output,
see Table 30.
When a STREAM file is opened, the first GET or PUT statement
can specify, with a statement option or format item, the first record
to be accessed. The statement option or format item indicates that n lines
are skipped before a record is accessed. The file is then positioned
at the start of the nth record. If no statement option
or format item is encountered, the initial file position is the
start of the first line or record. If the file has the PRINT attribute,
it is physically positioned at column 1 of the first line or record.
Opening a file that is already open does not affect the file.
- TITLE
- The content of expression determines what is being
designated. For more information on the TITLE attribute refer to
the Programming Guide.
- LINESIZE
-
Converted to an integer value, specifies the length in bytes of
a line during subsequent operations on the file. New lines can be
started by use of the printing and control format items or by options
in a GET or PUT statement. If an attempt is made to position a file
past the end of a line before explicit action to start a new line
is taken, a new line is started, and the file is positioned to the
start of this new line. The default line size for PRINT file is
120.
The LINESIZE option can be specified only for a STREAM OUTPUT
file.
- PAGESIZE
-
Is evaluated and converted to an integer value, and specifies the
number of lines per page. The first attempt to exceed this limit
raises the ENDPAGE condition. During subsequent transmission to
the PRINT file, a new page can be started by use of the PAGE format
item or by the PAGE option in the PUT statement. The default page
size is 60.
The PAGESIZE option can be specified only for a file having the
PRINT attribute.
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