You identify records in data sets by:
Generally, if you use a key, you can specify either a complete key or a generic (partial) key. The exceptions to this rule are when you write a record to a KSDS or when you write a record by an alternate index path. In either of these cases you must specify the complete key in the RIDFLD option of the command.
When you use a generic key, you must specify its length in the KEYLENGTH option and you must specify the GENERIC option on the command. A generic key cannot have a key length equal to the full key length. You must define it to be shorter than the complete key.
You can also specify the GTEQ option on certain commands, for both complete and generic keys. The command then positions at, or applies to, the record with the next higher key if a matching key cannot be found. When accessing a data set by way of an alternate index path, the record identified is the one with the next higher alternate key when a matching record cannot be found.
Even when using generic keys, always use a storage area for the record identification field that is equal in length to the length of the complete key. During a browse operation, after retrieving a record, CICS® copies into the record identification area the actual identifier of the record retrieved. CICS returns a complete key to your application, even when you specified a generic key on the command. For example, a generic browse through a KSDS returns the complete key to your application on each READNEXT and READPREV command.
You can use the RBA and RRN options on most commands that access data sets. In effect, they define the format of the record identification field (RIDFLD). Unless you specify either the RBA or the RRN, the RIDFLD option should hold a key to be used for accessing a KSDS (or a KSDS or ESDS by way of an alternate index).
RBA specifies that the record identification field contains the relative byte address of the record to be accessed. A relative byte address is used to access an ESDS, and it may also be used to access a KSDS that is not opened in RLS access mode. All file control commands that refer to an ESDS base, and specify the RIDFLD option, must also specify the RBA option.
RRN specifies that the record identification field contains the relative record number of the record to be accessed. The first record in the data set is number one. All file control commands that refer to an RRDS, and specify the RIDFLD option, must also specify the RRN option.
[[ Contents Previous Page | Next Page Index ]]