5. OPERATION › 5.1 Operation Overview › 5.1.3 VSAM/ICF Catalog Scan Overview › 5.1.3.1 VCCVCNTL--ICF/VSAM Catalog Scan Control

5.1.3.1 VCCVCNTL--ICF/VSAM Catalog Scan Control

The VCCVCNTL module schedules the VSAM/ICF catalogs that are
to be scanned by the VCCVSCAN subtask.  VCCVCNTL's logic is
as follows:

    o  Checks to see if the master catalog name was provided
       in the parameters.  If not, the CAXWA chain
       (represents open catalogs) is scanned to determine the
       name of the master catalog and the device on which it
       is located.  The CAXWA chain is chained from the CVT;
       the master catalog is represented by the last CAXWA
       control block on the chain (forward pointer = 0).

    o  GETMAINs work areas for the VCCVSCAN subtasks called
       Task Activity Areas (TAAs).  The VSAMSUBT value is
       used to control the number of GETMAIN'd TAAs as well
       as the number of VCCVSCAN subtasks to ATTACH.

    o  The VCCVSCAN subtasks are ATTACHed.

    o  The first subtask begins scanning the master catalog.
       As it encounters user catalogs or BCS catalog
       pointers, the VCCVSCAN subtasks adds them to a list of
       catalogs called the Catalog Name Queue (CNQ).  CNQs
       are chained from the volume entry in the volume table
       that VCCNTRL built during initialization.

    o  After it has scanned all catalogs, VCCVCNTL will
       POST VCCNTRL to indicate that catalog scan processing
       has been completed.