VTAM Buffer Usage by Category workspace

The VTAM(R) Buffer Usage by Category workspace displays the usage of the IO buffer pool based on its contents.

The IO buffer pool manages the storage of all network input/output messages sent from application programs and across channel connections. All network traffic passes through this pool, regardless of its destination. This buffer pool also contains channel programs used to service locally attached devices. Because a great deal of activity takes place in IO00, it is very sensitive to dynamic fluctuations in traffic rates. Consequently, it is a prime candidate for tuning.

Examining the contents of this buffer pool can help a network capacity planner plan for more CSA, understand how applications are using the pool, and understand the network traffic activity. The values reported in these tables are obtained by processing the contents of the buffers themselves and the VTAM control blocks are examined to determine which of the two categories each of the buffers in the IO pool is to be associated with.

  • User Category: Each buffer in the IO00 Buffer Pool is examined to determine if it falls into each of the following areas:
    • Unallocated Buffers
    • Read Channel Program Buffers
    • Buffers with a Transmission Subsystem Control Block (TSCB)
    • Miscellaneous buffers that do not meet any of the criteria of the previously listed categories
    The relative percentage of buffers for each of these categories is calculated and displayed.
  • User Category 2: Each buffer in the IO00 Buffer Pool that contains a TSCB is examined to determine if it falls into each of the following areas:
    • System services control point (SSCP) traffic
    • Virtual route pacing response traffic
    • APPL(PLU) to same subarea resource traffic
    • APPL(PLU) to a different subarea resource traffic
    • APPL(SLU) to a different subarea resource traffic
    • Local SNA resource to a different subarea APPL traffic
    • Local non-SNA to a different subarea APPL traffic
    • Intermediate routing node traffic
    The relative percentage of buffers for each of these categories is calculated and displayed.

This workspace is displayed by right-clicking on the Link icon in the VTAM Buffer Pools Summary table and selecting VTAM Buffer Usage By Category.

This workspace displays the following views:

  • Usage by User Category: Displays a bar chart showing percentage of usage for each buffer type in User Category.
  • Usage by User Category 2: Displays a bar chart showing percentage of usage for each buffer type in User Category 2.
  • Usage by User Category Summary table: Displays a table showing collection time, description, and percentage of usage for each buffer type in User Category.
  • Usage by User Category 2 Summary table: Displays a table showing collection time, description, and percentage of usage for each buffer type in User Category 2.