In minimum mode, the kernel cannot support some functions, such as the z/OS shell and TCP/IP.

If you specify OMVS=DEFAULT in the IEASYSxx parmlib member and then re-IPL, the kernel services start in minimum mode and use the default values for all BPXPRMxx parmlib statements. See the BPXPRMxx section in z/OS MVS Initialization and Tuning Reference for information about the default values.

In minimum mode, a temporary file system named SYSROOT is used as the root file system. It is initialized and primed with a minimum set of files and directories. Any data written to this file system is not written to DASD. (See Managing the temporary file system (TFS) for a description of a temporary file system.) The temporary file system does not have any executables; that is, the shell will not be available. Do not install z/OS UNIX System Services Application Services in the TFS, because data will not be written to DASD.

To switch to using kernel services in full function mode, complete the tasks that are described in Setting up for full function mode. The task list in Table 1 applies to those who want to use full function mode.