OS Simulation › Introduction

Introduction

If you want to read or write multivolume data sets that were created on either VM or MVS, you must use CMS OS simulation. IBM's OS Simulation Standard Label Tape Processing Exits enable you use a tape management system such as CA VM:Tape with OS simulation.

There are two OS Simulation Standard Label Tape Processing Exits in CMS, the DMSTVI exit and the DMSTVS exit. DMSTVI supersedes DMSTVS and offers more features.

DMSTVI automatically generates a mount request for the first tape in the multivolume sequence based on information you supply on CMS FILEDEF and LABELDEF commands. Also, DMSTVI supports the SYSPARM parameter on the FILEDEF command, which allows you to specify CA VM:Tape MOUNT command options for the tape mounts that occur during the OS simulation. DMSTVS does not support the SYSPARM parameter and you must manually pre-mount the first tape in the multivolume sequence using the CA VM:Tape MOUNT command.

When reading a tape in a multivolume sequence, the exit and CA VM:Tape use chaining information in the TMC to mount subsequent tapes in the sequence when CA VM:Tape reaches the end of each tape. If you are creating a data set, CA VM:Tape keeps mounting scratch tapes until the data set is complete, then records the chaining information in the TMC.

This section contains information about using the DMSTVI and DMSTVS exits. It also contains information about the SYSPARM parameter on the FILEDEF command and on the SLMOUNT EXEC, which you can use to pre-mount tapes when using the DMSTVS exit.

Note: You cannot use OS simulation to work with tapes that are in the Bin system. For more information about OS simulation and the CMS command reference for your system for information about CMS commands, see the CMS User's Guide.