Creating BLOCK Control Files

After the BLOCK table file is built, you must determine in which of the BLOCK control files the new definition file name should reside, and what order position the file will occupy.

A maximum of four block table files can be used in a single block session.

The block control file is a file that tells BLOCK which block table files to load during initialization. The definition files loaded depend on the type of dump the user is currently examining. When BLOCK initialization starts, BLOCK uses the dump type to search a table called HCSTBL. See HCSTBL Table for more information on HCSTBL. When a match is found on the DUMPTYPE, the entry in the HCSTBL is checked for a block control file. If that exists, the suffix is appended to the characters HCS$ to form the file name of the control file name (the file type is always TABLE) for that dump type. BLOCK then searches for that control file and extracts the names of the block definition files for the dump. After you know the name of the control file for the dump being examined, you simply put the name of the new file in the order position desired. The position of the file is important. BLOCK searches for control block names sequentially. This means that the first definition file is searched first, the second searched second, and so on. After the BLOCK subcommand finds a match to the name entered on BLOCK invocation, the file search stops, and BLOCK maps the data based on that definition. BLOCK thus does not recognize duplicate names within a definition file.

After you have added the new definition file names, the file should be saved on a minidisk that is ahead of the original control file disk in the CMS search order.

The following is an example of a simple BLOCK control file. The file has records 80 bytes long.

**************************************************************
* The base CMS control blocks for z/VM                      *
**************************************************************
CMSBLOCK CBMAP

In this example, MYFILE CBMAP is added to a BLOCK control file:

**************************************************************
* The base CMS control blocks for z/VM                      *
**************************************************************
MYFILE CBMAP
CPMBLOCK CBMAP