CMS control files are used when no z/OS system is present. They are not addressable from a z/OS system. In z/VM systems, you may need to use a CMSFP format file, which is described in more detail in the next section.
If the CMS format control file is to be shared between a host z/VM system and its z/VM guest systems, you should use a single MDISK statement at the first level, and as many LINK statements as you need. Mode MWV should be specified on the MDISK statement, and MW on the LINK statements. Always use MWV mode when two or more guests on the same z/VM system will share the same control file, even if the control file will also be shared with a z/VM system running on another processor.
A CMS control file is placed at the top end of a CMS minidisk, in an area not used by the CMS file system. The MIMGR 191 minidisk should not be used for a CMS control file. Instead, define a minidisk that you will use only for control file purposes if you choose to use a CMS format control file.
Suppose you define a MIMGR 291 minidisk for a control file. The minidisk should be defined one cylinder larger than the size you will need for the control file. For this example, we will define a ten-cylinder control file, so the minidisk should be 11 cylinders long. To make the disk usable for control file use, perform the formatting steps shown here:
FORMAT 291 B#1#CTFL1 FORMAT 291 B 1 (RECOMP
This results in a CMS minidisk that is formatted for CMS files in the first cylinder only. The remaining ten cylinders are not available for CMS files on the minidisk. (The control file is not stored in CMS file format.) "CTFL1" is the minidisk label you are assigning to MIMGR 291. You may choose any label of six characters or less. The label you specify here will have to be matched on VMPROOF.
Note: The operation performed by the CMS FORMAT command only formats space for CMS file operations and reserves space for the control file. After this is done, it is still necessary for the first VMPROOF or MIMPROOF that starts operations to request a format in its parm field.
It is not necessary to access the minidisk before running VMPROOF because VMPROOF sends its own I/O to the minidisk without using the CMS file system. The same is also true for the CA MIM production program. Therefore, there is no need to have an ACCESS statement for control file disks in PROFILE GCS or PROFILE EXEC.
You can store CMS files in the CMS portion of the minidisk if you want to, and you can access this disk to use the files for CMS or GCS purposes, but remember that the disk will be unavailable at times when CA MIM is running, due to RESERVE contention. Files that CA MIM accesses, such as AUTHUSER MIM and UNITS MIM, should not be stored here.
To run VMPROOF tests of this control file, enter the following command:
VMPROOF 291 CMS F007 CTFL1
VMPROOF verifies the configuration of 291, formats the area beginning at cylinder 1, and then begins writing and reading simulated control file data.
You can issue a similar command on other z/VM systems or on other guests that share the control file to verify that serialization is working as you expect. As described above, the parameter F007 would have to be changed for each additional system you add to the test. Only the first system will use the letter "F" (others all use "N"), and each system uses a different second digit. Also, each system should use a different delay time.
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