You can use the /DBDUMP command with the DATABASE keyword to prevent programs from updating DL/I full function databases.
You can use the /DBRECOVERY command to prevent transactions or programs from accessing a database (with the DATABASE keyword) or a DEDB area (with the AREA keyword, which is valid with DEDBs only). The command closes and deallocates the database(s) or area(s), so that they are not authorized to DBRC.
If a specified database is being used when you enter either /DBDUMP or /DBRECOVERY, the thread currently using the database is allowed to complete, but no further PSB schedules are allowed.
If a database specified in either of these commands is being used by a BMP, an error message is issued, and the command is ignored for that database. You reenter the /DBDUMP or /DBRECOVERY command when the database is no longer being used by a BMP. If you need to recover the database immediately, use the /STOP command with the THREAD keyword (or its synonym, REGION) to terminate any BMPs using the database before you reenter the /DBDUMP or /DBRECOVERY command.
For a whole DEDB, the PSB is not scheduled. For a DEDB area, programs are not allowed access to data in that area. For a DL/I database, programs are not allowed access to the database.
The /START command reverses the effects of a /DBDUMP or /DBRECOVERY command. The /START command allocates the database or area. A database is authorized on the first schedule request it receives, and is opened at the first DL/I request. An area is authorized and opened on receipt of the first DL/I request.