Specifying SYS1.DUMPxx data sets

When planning SYS1.DUMPxx data sets, remember that the data sets frequently contain sensitive data (user or installation confidential information, logon passwords, encryption keys, etc.). Protect these data sets with RACF® to limit access to them.

The installation can specify SYS1.DUMPxx data sets in two ways:

IBM® recommends that you use the DUMPDS operator command through the COMMNDxx parmlib member. Use the DUMPDS ADD command within the COMMNDxx parmlib member to ensure that all interaction with the dump data set occurs through the DUMPDS command.
For example, to specifically add data set SYS1.DUMP05, enter:
```
   COM='DUMPDS ADD,DSN=05'
```
During system initialization, in the DUMP parameter in the IEASYSxx parmlib member.
Specify DUMP=NO in the IEASYSxx parmlib member. Otherwise, all available data sets will be allocated before the COMMNDxx parmlib member is processed.

The data sets are on direct access only. The maximum number of SYS1.DUMPxx data sets an installation can have is 100. The direct access data set must be on a permanently resident volume; that is, the data set must be allocated and cataloged. These dump data sets cannot be shared by more than one system.

All dump data sets should not be on the same pack. A pack should contain enough storage to allow the dump data sets to allocate secondary extent space, if needed.

For more information, see the following references:

See z/OS MVS Initialization and Tuning Reference for information about the IEACMDxx and IEASYSxx parmlib member.
See z/OS MVS System Commands for information about using the DUMPDS command.