You use the online DML FPASCAN and the SEARCH-MODE parameter of the SDF statement SET-FPA-SCAN-PARAMETERS to define the search mode for the free place search, i.e. the page in a realm from which space is searched for to store new records and tables which are caused by application programs through the DMLs MODIFY and STORE:
SEARCH-MODE=*REUSE specifies the start page for the free place search at the beginning of the realm (“Second Scan”). This offers an option of using free space (created, for example, by deleting records or tables) again immediately for new storage operations.
In the case of SEARCH-MODE=*NOREUSE the DBH switches to “First Scan” when the next checkpoint is reached. In this search mode space for the new data which is to be stored is searched for at the end of the realm, i.e. from the first page of the contiguous range of free pages at the end of the realm.