Keyword LIKEREC is used to define a data structure, data structure subfield,
prototyped return value, or prototyped parameter like a record. The subfields
of the data structure will be identical to the fields in the record. LIKEREC
can take an optional second parameter which indicates which fields of the
record to include in the data structure. These include:
- *ALL All fields in the external record are extracted.
- *INPUT All input-capable fields are extracted. (This is the default.)
- *OUTPUT All output-capable fields are extracted.
- *KEY The key fields are extracted in the order that the keys are defined on the K specification in the DDS.
*NULL may also be specified to indicate that instead of defining the subfields
with the same data types as the fields in the file, the subfields are all indicators.
For a database file, these indicators have the same layout as the null byte map for the record.
The following should be taken into account when using the LIKEREC keyword:
- The first parameter for keyword LIKEREC is a record name in the program. If the record name has been renamed, it is the internal name for the record.
- The remaining extract-type parameters for LIKEREC must match the definition of the associated
record of the file on the system. *INPUT is only allowed for input and update capable records;
*OUTPUT is only allowed for output capable records; *ALL is allowed for any
type of record; and *KEY is only allowed for keyed files. If not specified,
the parameter defaults to *INPUT.
However, when an extract-type parameter is not specified for a record name
from a DISK file, and the output
buffer layout exactly matches the input buffer layout, the data structure
may be used with a WRITE operation.
- For *INPUT and *OUTPUT without *NULL, subfields included in the data structure occupy the same start positions as in the external record description.
- If a prefix was specified for the file, the specified prefix is applied to the names of the subfields.
- When *NULL is specified, the indicators occupy the same start position as the null indicators in the
null byte map for the external record for a database file.
For other types of files, the start positions of the indicator subfields are assigned sequentially.
- Even if a field in the record is explicitly renamed on an input specification the external name (possibly prefixed) is used, not the internal name.
- If the file is defined with the ALIAS keyword, the alias names will be used for the subfields of the data structure. Using the ALIAS keyword for an externally-described file shows an example defining a data structure with the LIKEREC keyword where the file is defined with the ALIAS keyword.
- A data structure defined with LIKEREC is a QUALIFIED data structure. The names of the subfields will be qualified with the new data structure name, DS1.SUBF1.
- LIKEREC can be coded for subfields of a qualified data structure. When LIKEREC is coded on a data structure subfield definition, the subfield data structure is automatically defined as QUALIFIED. Subfields in a LIKEREC subfield data structure are referenced in fully qualified form: "ds.subf.subfa". Subfields defined with LIKEREC are themselves data structures, and can be used wherever a data structure is required.
- Data structures defined with the extract-type *NULL cannot be used with I/O operations.