Use ISMF to create your SCDS base. The starter set configuration can be used as a model for your own SCDS. The panels displayed in this section reflect data from this sample configuration.

Related Reading: For a detailed description of base configuration attributes and how to use ISMF to define its contents, see z/OS DFSMSdfp Storage Administration.

Follow these steps to create the SCDS base:

1. Enter an 8 (Control Data Set) on the ISMF Primary Option Menu to view the CDS Application Selection panel shown in Figure 1.

   Requirement: You must have the correct RACF® authorization. If your ISMF menu does not display option 8 (Control Data Set), select option 2 to define yourself as a storage administrator. You might need to exit ISMF and ISPF for the change to take effect.

   Figure 1. CDS Application Selection Panel

     Panel  Utilities  Help                                                      
   ------------------------------------------------------------------------------
                             CDS APPLICATION SELECTION                           
   Command ===>                                                                  
                                                                                 
   To Perform Control Data Set Operations, Specify:                              
     CDS Name . . MYSCDS                                                         
                               (1 to 44 Character Data Set Name or 'Active')     
                                                                                 
   Select one of the following Options:                                          
        1. Display       - Display the Base Configuration                        
        2. Define        - Define the Base Configuration                         
        3. Alter         - Alter the Base Configuration                          
        4. Validate      - Validate the SCDS                                     
        5. Activate      - Activate the CDS                                      
        6. Cache Display - Display CF Cache Structure Names for all CF Cache Sets
        7. Cache Update  - Define/Alter/Delete CF Cache Sets                     
        8. Lock Display  - Display CF Lock Structure Names for all CF Lock Sets  
        9. Lock Update   - Define/Alter/Delete CF Lock Sets                      
   If CACHE Display is chosen, Enter CF Cache Set Name . . *                     
   If LOCK Display is chosen, Enter CF Lock Set Name . . . *                     
                                (1 to 8 character CF cache set name or * for all)
   Use ENTER to Perform Selection;                                               
   Use HELP Command for Help; Use END Command to Exit.                           

2. In the CDS Name field, type in the name of the SCDS that is to contain the base configuration. In this example, the CDS name is YOUR.OWN.SCDS. Enter a 2 (Define) to view the SCDS Base Define panel shown in Figure 2.
   Figure 2. SCDS Base Define Panel, Page 1 of 2

      Panel  Utilities  Scroll  Help
    ------------------------------------------------------------------------------
                                  SCDS BASE DEFINE                 Page 1 of 2
    Command ===>
   
    SCDS Name . : YOUR.OWN.SCDS
    SCDS Status : VALID
   
    To DEFINE SCDS Base, Specify:
   
     Description ===> This is the configuration used to implement a
                 ===> minimal configuration
   
     Default Management Class  . . STANDEF   (1 to 8 characters)
     Default Unit  . . . . . . . . SYSDA     (esoteric or generic device name)
     Default Device Geometry
       Bytes/Track . . . . . . . . 56664     (1-999999)
       Tracks/Cylinder . . . . . . 15        (1-999999)
     DS Separation Profile                   (Data Set Name)
     ==>_________________________________________________________
   
   
    Use ENTER to Perform Verification; Use DOWN Command to View next Panel;
    Use HELP Command for Help; Use END Command to Save and Exit; CANCEL To Exit.

   Use the DOWN command to view the second page as shown in Figure 3.

   Figure 3. SCDS Base Define Panel, Page 2 of 2

      Panel  Utilities  Scroll  Help
    ------------------------------------------------------------------------------
                                  SCDS BASE DEFINE                 Page 2 of 2
    Command ===>
   
    SCDS Name . : YOUR.OWN.SCDS
    SCDS Status : VALID
   
    Specify one of the following options . . 1         (1 Add, 2 Delete, 3 Rename)
   
      Specify System Name . . . . . SYSTEM6   or Sys Group Name . .
   
      New System/Sys Group Name . .           (For option 3, Rename)
   
    System: SYSTEM1  SYSTEM2  SYSTEM3  SYSTEM4  SYSTEM5  SYSTEM6  SYSTEM7  SYSTEM8
   
   
   
    Sysgrp: SYSPLX01 SYSPLX02
   
   
   
    Use ENTER to Perform Option; Use UP Command to View previous Panel;
    Use HELP Command for Help; Use END Command to Save and Exit; CANCEL To Exit.

   The SCDS name is the same as the value that you specified on the CDS Application Selection panel (see Figure 1).

3. Define a default management class and type it in the Default Management Class field. In this example, we have used the STANDEF management class, a management class in the sample configuration.

   The default management class is only used when DFSMShsm performs automatic processing for those data sets that do not have management classes assigned to them. When no management class is assigned to a data set, the catalog entry for that data set contains no management class, even though the default management class controls its backup and availability. You should periodically search for data sets that are system-managed and have no management class assigned. DFSMSdss's filtering capabilities can be used to identify system-managed data sets with no management class assigned, and to produce a report containing these management class exceptions.

4. You should set the value in the Default Unit field to your system's primary esoteric name. For Default Device Geometry, specify values for the Bytes/Track and Tracks/Cylinder attributes. The values for the 3380 are 47476 and 15, respectively. For the 3390, the values are 56664 and 15, respectively.

   You should indicate the characteristics of your predominant device as the characteristics for the default unit. If your configuration contains 90% 3390-2s and 10% 3380-Ks, then specify the 3390 geometry characteristics as the default device geometry.

   The JCL UNIT parameter is optional for new data set allocations for both system-managed and non-system-managed data sets. SMS uses the Default Unit attribute if no unit is specified when allocating non-system-managed data sets. The Default Device Geometry attribute converts an allocation request from tracks or cylinders to KBs or MBs when an esoteric unit is used, or when no unit is given. Through this conversion, uniform space can be allocated on any device type for a given allocation.

   The space request is always converted to KBs or MBs according to the following formula:

                               (# tracks x (bytes/track))
   tracks allocated = ____________________
                                track capacity

   Where:

   • bytes/track is derived from the Default Device Geometry attribute.
   • track capacity is the capacity of the device selected, including device overhead.
   • The result of the calculation, tracks allocated, is rounded up.
   This change can affect your user's existing JCL that specifies the UNIT parameter. There are two variations of UNIT coding:

   • Users specify a generic name, such as 3380 or 3390:

     These users have allocation converted to bytes, based on the geometry of that device.

   • Users specify an esoteric name, such as SYSDA:

     These users have allocation converted to bytes, based on the Default Device Geometry attribute.

     Use an esoteric name for a more consistent amount of allocated space. It provides a transition for users to allocation in the system-managed storage environment.

5. If you have created a data set separation profile, use the optional field DS Separation Profile to provide SMS with the name of the profile. During volume selection for data set allocation, SMS attempts to separate, on the PCU or volume level, the data sets that are listed in the data set separation profile.

   You can specify any valid sequential or partitioned member data set name, with a maximum length of 56 characters, with or without quotation marks. For data set names without quotation marks, ISMF will add the TSO user ID prefix of the person who is defining or updating the base configuration.

   The default value is blank, which indicates that data set separation is not requested for the SMS complex.

   Recommendation: Use data set separation for a small set of mission critical data only.

   Related Reading: To learn how to create a data set separation profile, see Using Data Set Separation in z/OS DFSMSdfp Storage Administration.

6. Use the System Name or Sys Group Name and New System/Sys Group Name fields to define the SMS system or system group. You can define up to 32 system names and system group names in the SCDS base, depending on whether you are running in compatibility or 32-name mode. When the system is running in compatibility mode, you can only define up to eight system or system group names. When the system is running in 32-name mode, you can define up to 32 system names or system group names, as follows:
   • The system name must match the GRS system ID.

     Related Reading: For a description of the GRS SYSNAME parameter in the IEASYSxx member of the SYS1.PARMLIB, see z/OS MVS Initialization and Tuning Reference.

   • The system group name must match the name of the Parallel Sysplex®. The Parallel Sysplex name is defined in the COUPLExx member of the PARMLIB of each of the systems that belong to the Parallel Sysplex.

     Restriction: In a JES3 environment, system group name is not supported due to the fact that the system features and resources that are used to determine on which eligible system a job will be run are only applicable to each system, not to a system group.