z/OS Storage Administration
Part Three - Challenge #08


An enterprise z/OS environment has thousands of disk volumes and thousands of tape volumes. These thousands of disk volumes and tape volumes are capable of storing millions of data sets.

A critical z/OS base component is DFSMS, Data Facility Storage Management Subsystem. The contest challenge will only scratch the surface of DFSMS. The fact that you are even aware of DFSMS as a critical z/OS component would impress any perspective employer.

DFSMS is a very broad category of data management technology that far exceeds data management services in other operating systems.

The Storage Management Subsystem (SMS) is part of DFSMS. SMS changes the storage management approach from user-managed volumes to SMS-managed data sets residing in SMS-managed storage groups. The system, rather than the user, determines data placement and handles data backup, movement, space, and security.

SMS provides the following storage classes and groups, which are customized by the storage administrator to fit the system environments and policies:

  • Data class: A list of allocation attributes that the system uses for the creation of data sets.
  • Storage class: A list of storage performance and availability service requests.
  • Management class: A list of data set migration, backup, and retention attributes that DFSMShsm uses to manage storage at the data set level.
  • Storage group: A list of real DASD volumes, or a list of serial numbers of volumes that no longer reside on a system but that end users continue to refer to in their JCL.

Storage administrators also customize SMS automatic class selection (ACS) routines, which automatically assign the SMS classes and storage groups to data sets. This allows the user to create data sets by providing only a small amount of information through ISMF panels.

ISMF, Interactive Storage Management Facility, are panels available to a storage administrator to assist with managing and monitoring disk storage capacity. ISMF is a manadatory skill for z/OS Storage Administrators.

This challenge exposes you to Storage Management Subsystem (SMS). This knowledge will begin to qualify you as a disk administrator candidate. If you were to interview for a large enterprise disk storage administrator position, the hiring authority would be impressed that you would have this knowledge.

SMS significantly simplifies JCL through implemented standards. An example is system customization that has data set name rules for new data set allocations. The challenge demonstrates system implemention of data set name rules for newly allocated data sets that ONLY require data set name and disposition of new on the JCL DD statement. The system customization results in determining data set volume placement, data set attributes, and data set space. Without this SMS customization, a newly allocated data set requires volume, attributes, and space values on the JCL DD statement.


  1. Edit hlq.JCL
  2. Select new member name, p3ch8
  3. Copy JCL into empty member name
  4. Observe the member has 2 JCL jobs that are nearly identical with data set name exception
    Submit the 2 JCL jobs and jump to SDSF to review output
  5. Review the JCL job output
  6. Observe JCL job P3CH8A messages in JESYSMSG about failure to allocate data set with 2nd data set qualifier of NEWDS
  7. F3 to return to SDSF ST panel, ? P3CH8B, and select JESYSMSLG
    Observe JCL job P3CH8B messages in JESYSMSG that successfully allocated data set with 2nd data set qualifier of SEQ
  8. The above output has message IGD101I which means this new allocation was handled by Storage Management Subsystem (SMS).
      The message referenced STORCLAS(MTMSEQ) and DATACLAS(MTMSEQ) - whatever that means
      The message referenced a disk volume where the data set was placed, MTM004
      Explanation follows

SMS is configured, customized, and maintained by the Storage Administrator. The configuration and customization are agreed upon storage rules which would be documented and shared with the IT staff for their use. A storage rule on this system is that any data set name with a 2nd data set name qualifier of SEQ is assigned data set attributes, data set space, and a volume where the data set will be allocated.

z/OS data set allocation processing rules enforced by SMS configuration and customization consist of control data sets and processing logic. The control data sets are VSAM data sets used to define resources such as MTMSEQ associated with data set attributes and space. The processing logic is known as the SMS Automatic Class Selection (ACS) routines. The logic is interpretitive script language stored in partitioned data set members.

SMS Control Data Sets sections include:

  1. Data Class definitions
  2. Storage Class definitions
  3. Management Class definitions
  4. Storage Group definitions

SMS Control Data Sets also store the partition data set names and member names of the ACS routine processing logic.

Automatic Class Selection (ACS) routine processing logic includes:

  1. Data Class processing logic
  2. Storage Class processing logic
  3. Management Class processing logic
  4. Storage Group processing logic

ISMF, Interactive Storage Management Facility, panels are available to review the SMS Control Data Set defintions and Automatic Class Selection (ACS) routines which is the processing logic.

  1. Select ISMF panels from ISPF Primary Option Panel
  2. Select Option 4 - Data Class
  3. 'ACTIVE' CDS name, Control Data Set, are DATA CLASS definitions actively used by the system.
    The asterisk (*) is to list all Data Class definition entries.
    ENTER to proceed through ISMF panels.
  4. The list of DATA CLASS entries includes many columns with the defined attributes for the entry.
    Observe the Data Class definition for MTMSEQ with RECFM (FB), LRECL (80), AVGREC (K) and AVG VALUE (1)
    Enter view command below to include only columns 4 5 12 26 and 46.
  5. Observe the MTMSEQ DATA CLASS definition with the blank DATA SET NAME TYPE.
      Blank defaults to a sequential data set name type.
      OVERRIDE SPACE value of YES means SMS discards any JCL DD SPACE value and SPACE is determined ONLY by what is in this DATA CLASS definition.
      F3 until back at the ISMF PRIMARY OPTION MENU.
  6. Select 0 - ISMF PROFLE
  7. Select 0 - User Mode Selection
  8. Change User Mode from 1 (End User) to 2 (Storage Administrator)
      ENTER after typing in the mode change
      F3 until back to ISPF Primary Option Menu - required for setting to take effect
  9. Again, select ISMF panels from ISPF Primary Option Panel
  10. Observe more options now that User Mode was changed to Storage Administrator
      Select option 7 - Automatic Class Selection
  11. Select 5 to Display data set name and member names of the ACS processing logic
  12. Observe:
      ZOS.PUBLIC.SMS.ROUTINES is the "source" data set name for the ACS routines
      ACSSTORD is the member with DATACLAS processing logic
      ACSSTORC is the member with STORCLAS processing logic
      ACSSTORG is the member with STORGRP processing logic
      F3 until back to the ISPF Primary Option Menu
  13. Jump to Data Set List Utility panel
  14. Enter data set name where ACS processing logic members are located
  15. Browse b the partitioned data set with the ACS processing logic members
  16. Select s each member to see the ACS processing logic
  17. This is what SMS Automatic Class Selection processing logic looks like
    F3 to move on to the next selected member
  18. DATA CLASS ACS routine, ACSSTORD, and the DATA CLASS definition, MTMSEQ, is the reason why newly allocated hlq.SEQ.TEST only required the data set name and the disposition of new, catalog on the JCL DD statement when hlq.NEWDS.TEST failed to allocate


    SMS saw the data set name 2nd level qualifier, SEQ, and applied the data set attributes from the SMS DATA CLASS definition, MTMSEQ

    Previously panels displayed MTMSEQ DATA CLASS definition as a sequential data set type with other data set attributes such as space, etc.

    F3 to proceed to next ACS member
  19. ACSSTORG, Storage Group, ACS processing logic assigns the physical volumes for allocation.   MTM is a STORAGE CLASS definition that has disk volumes labels to be used for all allocations assigned to STORGRP 'MTM'.

    F3 until back to ISPF Primary Option Menu.

You just completed a review of SMS and ISMF that IT professionals attend a several day professional training class to acquire knowledge on. You are prepared to work with an experienced z/OS Storage Administrator armed with comprehension of SMS and ISMF.

The details you just reviewed has the technicals details to accomplish a simple task to complete this challenge.

  • Edit hlq.JCL member name P3CH8
  • Delete lines 4 to 7
  • Change line 3 data set name middle level qualifier from NEWDS to a middle level qualifier that will be processed by SMS environment to allocate a new partitioned data set with only the DSN=data_set_name and DISP=(NEW,CATLG) in the the JCL DD statement
  • Submit and review output until successful new partitioned data set is allocated with only the data set name and DISP=(NEW,CATLG)

Once the above is completed, then tso submit 'zos.public.jcl(p3ch8x)' to write a list of your data set names into P3.OUTPUT(#08) which includes the newly allocated partitioned data set name.

Next: Challenge #09