You request that the system begin its search with a specified starting location and continue for a certain number of records or tracks. You can use the extended search option to request a search for unused space where a record can be added.

To use the extended search option, you must specify in the DCB (DCBLIMCT) the number of tracks (including the starting track) or records (including the starting record) that are to be searched. If you specify a number of records, the system might actually examine more than this number. In searching a track, the system searches the entire track (starting with the first record); it therefore might examine records that precede the starting record or follow the ending record.

If the DCB specifies a number equal to or greater than the number of tracks allocated to the data set or the number of records within the data set, the entire data set is searched in the attempt to satisfy your request.

In addition to the relative track or block address, you specify the address of a virtual storage location containing the record key. The system computes the actual track address and searches for the record with the correct key.