Hello Vijay,
we have the work file database (called DSNDB07, except in a data sharing environment) is used for temporary space for certain SQL operations, such as join and ORDER BY.
Please check the following notes for further info on temporal tables
593469 DB2/390: Usage of global TEMP tables and related
141590 - DB2/390: SQLCODE -904 (Temporary space is too small)
794179 DB2-z/OS: BW: Tablespace is too small for temporary tables
regards,
Javier