Before you begin: Use the library manager console to ensure that the ranges of stacked volumes for containers are defined correctly. By doing so, you can avoid accidentally entering stacked volumes into the library as physical volumes.

Recommendation: Always define stacked volumes to DFSMSrmm. This ensures that the volumes cannot be used outside of the VTS. It also ensures that DFSMSrmm checks at cartridge entry processing time that a physical volume or logical volume does not duplicate a stacked volume.

You can define stacked volumes whether stacked volume support is enabled or not. Once stacked volumes are defined, DFSMSrmm records export, copy export, and import results only for the predefined stacked volumes. Once stacked volume support is enabled, DFSMSrmm automatically defines exported and copy exported stacked volumes to record details of this activity. There is no automatic host notification when stacked volumes enter the VTS, leave the VTS, or change category, so you must use DFSMSrmm commands if you want to have all stacked volumes defined to DFSMSrmm.

To define stacked volumes to DFSMSrmm and ensure that they can only be used as stacked volumes inside a VTS, perform these steps:

1. Issue the RMM ADDVOLUME subcommand with the TYPE(STACKED) operand to manually define stacked volumes to DFSMSrmm.
2. Take one of these steps to prevent the use of stacked volumes outside the VTS:
   • Specify the DFSMSrmm EDGRMMxx parmlib command OPENRULE VOLUMERANGE('start':'end') TYPE(ALL) ANYUSE(REJECT) to prevent the use of ranges of stacked volumes.
   • Specify the DFSMSrmm EDGRMMxx parmlib command REJECT ANYUSE(*) to prevent the use of any volumes not defined to DFSMSrmm. See Defining tapes not available on systems: REJECT.
     Note: If you use REJECT commands, you have to convert from the use of REJECT commands in order to use the PRTITION and OPENRULE commands. See Converting REJECT commands to PRTITION and OPENRULE commands for information about converting from the use of REJECT commands.
   • Specify the DFSMSrmm EDGRMMxx parmlib command REJECT ANYUSE(prefix*) to prevent the use of ranges of stacked volumes.
   • Specify the RMM ADDVOLUME subcommand with the USE(VM) operand and the TYPE(STACKED) operand to manually define stacked volumes that cannot be used on z/OS to DFSMSrmm.