PoolView

Using the Product in a CICS Environment › Analyze CICS Data › PoolView

PoolView

CICS file (or database) accesses are usually the cause of most of the internal processing delays. CICS transactions can access any type of file but usually retrieve their data from VSAM files or a database management system such as IMS/DB or DB2®.

The VSAM response time is especially sensitive to several key definitions, including

Number of index buffers
Number of data buffers
Number of strings
CI size
CI and CA splits

CA Mainframe Application Tuner provides statistics on these critical parameters that can help improve the performance of a transaction.

See also "File and Database Statistics". These statistics can be used to measure the effectiveness of tuning measures (such as file I/O times).

You can access CICS VSAM files by using a facility called Local Shared Resources (LSR). This feature creates a buffer pool in the monitored program’s region that can be shared by a number of VSAM files. The number of buffers and strings that you define for the pools can critically affect a transaction’s performance. CA Mainframe Application Tuner allows you to look into your LSR pool with PoolView, which lists each group of buffers and their usage statistics.

From the Interactive Analysis menu, select Option 8.

The PoolView panel displays:

CA MAT -------------------------- PoolView ------------------ ROW 1 to 1 of 1 COMMAND ===> SCROLL ===> CSR Line commands: S - Select Profile: CICSMIX Options: NORMAL LC Type Group Category ____ _____ _____________________________________ ------------------------------------------------------------------------------- __ VSAM LSR VSAM Local Shared Resource pool

Type S.

Press Enter.

The Shared Pools panel displays.

CA MAT ------------------------ Shared Pools ---------------- ROW 1 to 4 of 4 COMMAND ===> SCROLL ===> CSR Pool type: LOCAL Profile: CICSMIX Total pool size: 81408 Options: NORMAL Hit ratio for all subpools: 67.0% Line commands: S - Select, D - Datasets Pool No. of Buffer Buffer No. Requests Requests Hit LC Type Group SP Type Buffers size fixed Str w/read wo/read Ratio ____ _____ ___ _____ _______ ______ ______ ___ _________ _________ _____ >------------------------------------------------------------------------------ __ VSAM LSR 1 BOTH 3 512 NO 1 843 1,717 67.0% __ VSAM LSR 1 BOTH 3 2,048 NO 1 0 0 *N/A* __ VSAM LSR 1 BOTH 3 20,480 NO 1 0 0 *N/A*

High hit ratios indicate that a significant portion of the read requests are satisfied from buffers rather than from DASD. You can relate VSAM files to a buffer pool by using the data and index CI sizes from the DataView detail panels. If a file indicates large delays, you can alter the number of buffers that are allocated for the CI size that the file uses.

To look at more detailed information about a VSAM pool, type S and press Enter.

The VSAM Pool Details panel displays. VSAM Pool Details displays the same information as shown in Shared Pools, but in a detail format.

CA MAT -------------------------- VSAM Pool Details -------------------------- COMMAND ===> Pool type: VSAM Profile: CICSMIX Pool group: LSR Pool ID: 1 Number of buffers: 3 Buffer size: 512 Number of strings: 1 Placeholders in chain: 0 Hit Ratio: 67.0% Requests requiring a read: 843 Requests satisfied from pool: 1717 User initiated writes: 0 Non-user initiated writes: 0 Retrieves by RBA: 0 ESDS inserts: 0 Retrieves by key: 0 KSDS inserts: 0 Buffer alters: 0 VSAM GETS: 0 Buffer searches: 0 Error buffers in pool: 0 Maximum error buffers: 0

To view a list of VSAM data sets that are opened by using the specified pool, type D and press Enter.

The Pooled Data Sets panel displays. Each of the data sets uses the buffers provided by this pool for its I/O.

CA MAT ------------------ Pooled Data Sets ----------------- ROW 1 to 2 of 2 COMMAND ===> SCROLL ===> CSR Subpool: 1 BufferSize: 512 Profile: CICSMIX Line commands: S - Select LC DDname Data Set Name Type Comp CISize ________ ____________________________________________ ____ ________ ______ ------------------------------------------------------------------------------- __ ACCTIX TUN.CICSTEST.INDEX.ACIXFILE KSDS INDEX 512 __ ACCTIX TUN.CICSTEST.DATA.ACIXFILE KSDS DATA 512

The fields on the Pooled Data Sets panel are described next.

Subpool

Identification number of the VSAM subpool.

Buffer size

Size in bytes of each buffer in the subpool.

DDname

DDNAME used to allocate the data set.

Data Set Name

full name of the data set

Type

One of the following VSAM data set types:

KSDS - a key sequenced data set that always accompanied by an INDEX component; the index component does not have to use the same subpool.
ESDS - an entry sequenced data set.

Comp

One of the following types:

DATA .ntains indexing information

CISize

Control Interval Size

This field shows the unit of transfer for VSAM data to and from storage. It is always a multiple of 512 bytes.

Type S next to one of the DD statements and press Enter to display an enhanced version of the Data Set Details panel.

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