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KSAM files are accessed from COBOL programs through calls
to a set of procedures. These procedures allow you to open, open
for shared access, write records to, read records from, lock, unlock,
update, position, and close a KSAM file. The COBOL procedures provided with
KSAM/3000 correspond to the INDEXED I/O module statements in COBOL 74.
In HP COBOL/3000, the procedures that are used to access KSAM
files differ in form from the COBOL input/output statements used
to access non-KSAM files. The KSAM interface procedures use parameters
for information that would otherwise be specified in the FILE-CONTROL
paragraph and the FD entry of the DATA DIVISION. These parameters are
themselves defined in the WORKING-STORAGE section of the DATA DIVISION.
The main restriction on the KSAM interface call parameters is that
they must be 16 bit aligned.
The KSAM interface procedures are called using a CALL statement of the
following general form.
CALL "name" USING filetable, status [,parameter[,...] ]
Where:
- "name"
identifies the procedure to which control is transferred. - filetable
an 8-halfword table that identifies the file by name and in which
access mode and input/output type are specified, and to which is returned
the file number on open, and a code identifying the previous
operation. - status
One halfword to which a two-character code is returned that indicates
the status of the input/output operation performed on the file by the
called procedure. - parameter
One or more parameters, depending on the particular procedure called,
that further define operations to be performed on the file.
The first two parameters, filetable and status,
are included in every KSAM procedure call except CKERROR; other
parameters may be specified depending on
the particular procedure. If a parameter is included in the procedure
format, then it must be included in the procedure call. All parameters
are required.
Another characteristic of KSAM procedure call parameters is
that they must always start on a halfword boundary. In order to
ensure this, the parameters should be defined in the WORKING-STORAGE
SECTION as 01 record items, 77 level elementary items, or else the
SYNCHRONIZED clause should be included in their definition.
A literal value cannot be used as a parameter to these procedures.
Any value assigned to a data item used as a parameter is passed
to the procedure, but a literal value causes an error.
Depending on the procedure, certain data items may be assigned
values as a result of executing the procedure.
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NOTE: There are no COBOL procedures to read a KSAM file in physical
order or to access a record by its physical record number. (Physical order is
the order in which the data records were written to the file.)
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