Requirements

Prior to invoking this service, your routine must do the following:

Initialize all storage described by a BLSRPWHS mapping macro. BLSRPWHS produces data constants when invoked within a CSECT to assist with this.
Place a description of the address space of interest in the format defined by macro BLSRDATS into field with suffix AS, and place the address of interest in the field with suffix LAD.
Update any options designated through the field with suffix PFLG to indicate the processing desired. APAR OA17842 adds support for flag bits DTYF (all selection bits), DTYFL (MODULE selector), DTYFM (STRUCTURE selector), and DTYFU (AREA selector) to permit the caller of the WHERE service to limit relationships that WHERE is to consider.