OSAM-Buffer-Pool report (for batch regions only)

The OSAM-Buffer-Pool report describes the OSAM buffer pool activity during an application's execution. This report is only written for programs running in batch regions.

Using the OSAM-Buffer-Pool report

The primary use of the OSAM-Buffer-Pool report, an example is shown in the following example, is to see how many OSAM I/O operations were issued. This report does not, however, show Sequential Buffering (SB) related information.

    *** OSAM DATA BASE BUFFER POOL STATISTICS ***
 FIX BLOCK DATA                                      Y/Y
 SUBPOOL ID                                         O04K
 SUBPOOL BUFFER SIZE                                4096
 TOTAL BUFFERS IN SUBPOOL                           1000
 
 
 LOCATE-TYPE CALLS                               1765296
 REQUESTS TO CREATE NEW BLOCKS                         0
 BUFFER ALTER CALLS                               340800
 PURGE CALLS                                       39371
 LOCATE-TYPE CALLS, DATA ALREADY IN SUBPOOL      1370897
 BUFFERS SEARCHED BY ALL LOCATE-TYPE CALLS       1987604
*READ I/O REQUESTS                                375355
*SINGLE BLOCK WRITES BY BUFFER STEAL RTN               0
*BLOCKS WRITTEN BY PURGE                          150284
 TOTAL NBR OF I/O ERRORS FOR THIS SUBPOOL              0
 BUFFERS LOCKED DUE TO WRITE ERRORS                    0
 LOCATE CALLS WAITED DUE TO BUSY ID                 1431
 LOCATE CALLS WAITED DUE TO BUFR BUSY WRITE            0
 LOCATE CALLS WAITED DUE TO BUFR BUSY READ             0
 BUFR STEAL/PURGE WAITED FOR OWNERSHIP RLSE          296
 BUFFER STEAL REQUEST WAITED FOR BUFFERS               0
 
*TOTAL I/O OPERATIONS                             525639

Fields in the OSAM-Buffer-Pool report

The figure is an example of an OSAM-Buffer-Pool report.

The OSAM-Buffer-Pool report is identical to the Database-Buffer-Pool report written by the DB monitor, with the following exceptions:

  • The field names in the IMS Monitor's Database-Buffer-Pool report are preceded by NUMBER OF, although the fields have the same meaning in both reports.
  • The //DFSSTAT OSAM-Buffer-Pool report does not keep track of the start trace and end trace times. This is unnecessary because information is always gathered for the //DFSSTAT reports from the beginning to the ending of the application's execution.
  • In addition, the //DFSSTAT OSAM-Buffer-Pool report contains a TOTAL I/O OPERATIONS field, which equals the sum of the following fields:
    • READ REQUESTS ISSUED
    • OSAM WRITES ISSUED
    • QUEUED WRITES ISSUED
    • FORMAT LOGICAL CYLINDER REQUESTS
    • BISAM READS OR QISAM SETLS.

    These fields represent I/O operations and are highlighted on the left by an asterisk (*).