Shared Pools

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The Shared Pools subpage displays statistics on VSAM and IMS/OSAM shared buffer pools.

• Type
  May be one of the following types of pools:

  • VSAM
    VSAM shared resources pool

  • IMS
    A VSAM pool used for IMS databases

• Group
  Defines the pool group type:

  Type	Description
  LSR	A VSAM Local shared resources pool
  GSR	A VSAM Global shared resources pool

• SP
  The identification number of the VSAM subpool.

• Pool Type
  Refers to the type of buffer pool. May be one of three values:

  • INDEX
    Buffers are used for Index control intervals

  • DATA
    Buffers are used for Data control intervals

  • BOTH
    Buffers are used for both Data and Index control intervals

• No. of Buffers
  The number of buffers for the buffer pool.

• Buffer size
  The size of each buffer in the subpool.

• Buffer fixed
  Indicates if the buffer pool resides in fixed storage:

  • YES indicates that the buffer group is in fixed storage.

  • NO indicates that the buffer group is not in fixed storage.

• No. Str
  The maximum number of requests that may execute in parallel for this buffer pool.
  This can become a problem with either too many or too few strings. If there is a potential for multiple requestors to execute within the pool and not enough strings are defined, then the requestors will wait. If there are not enough buffers to satisfy the demands placed on the pool by the number of requestors, the performance of all users may suffer.

• Requests w/read
  The number of user reads during the monitored period that required the buffer be read from DASD.

• Requests wo/read
  Displays the number of user reads during the monitored period that did not require the buffer to be read from DASD.

• Hist Ratio
  Displays the percentage of time that READ requests were honored without a physical I/O. The calculation is as follows:
  (Requests_w/read + Requests_wo/read) /Requests_wo/read

• Non-user writes
  The number of writes done by VSAM to reclaim buffers when enough buffers were not available for other operations.
  These writes are also referred to as VSAM STEAL writes. A value greater than 0 indicates a poorly performing VSAM data set.

• User init. writes
  The number of writes during the monitored period explicitly requested by the user. A user initiated write occurs if (for example) the program requests the buffers to be flushed at some point during the work in progress.

• Retrieves by RBA
  The number of writes during the monitored period explicitly requested by the user. A user initiated write occurs if (for example) the program requests the buffers to be flushed at some point during the work in progress.

• ESDS inserts
  The number of records written to the data set by Relative Block address. An ESDS data set is an Entry Sequenced Data Set.

• Retrieves by key
  Displays the number of records read during the monitored period by key from a KSDS.

• KSDS inserts
  The number of records written to a KSDS data set during the monitored period. A KSDS data set is one that is organized by key.

• Buffer alters
  The number of buffer alters that took place during the monitored period.

• VSAM Gets
  Displays the number of VSAM Get requests that occurred during the monitored period.

• Buffer searches
  Displays the number of buffer searches that occurred during the monitored period.

• No. PLH in chain
  The number of Place Holders that are concurrently in the lock chain.

• Error buffs in pool
  The current number of error buffers in the pool.

• Max error buffs
  The maximum number of error buffers in the pool at any point in time.