ATPSB is a standard SAP Structure so does not store data like a database table does. It can be used to define the fields of other actual tables or to process "ATP Server: 'Shared Buffer' Table for VBBE ..." Information within sap ABAP programs. This is done by declaring abap internal tables, work areas or database tables based on this Structure. These can then be used to store and process the required data appropriately. i.e. DATA: wa_ATPSB TYPE ATPSB.
The ATPSB table consists of various fields, each holding specific information or linking keys about ATP Server: 'Shared Buffer' Table for VBBE ... data available in SAP. These include RELID (Region in IMPORT/EXPORT Data Table), ATPMD (Client), ATPTK (ATP Server: Key for table in 'shared buffer'), WERKS (Plant)... See below for full list along with technical details, documentation, text table, check tables, foreign key relationships, conversion routines, relevant tcodes and example ABAP select code etc. .