(1) .-IQDIOSTG--=--MAX-------. >>-+------------------------+---------------------------------->< '-IQDIOSTG--=--+-MAX-+---' +-AVG-+ +-MIN-+ '-nnn-'
Specifies how much storage VTAM® keeps available for read processing for all HiperSockets™ data devices that use a MFS (Maximum Frame Size) of 64k. The HiperSockets MFS is defined in HCD. The HiperSockets storage units are defined in QDIO SBALs (QDIO read buffers). Each SBAL is 64k. For most users, the default setting will be the most suitable option. The storage used for this read processing is allocated from CSM data space 4k pool, and is fixed storage.
HiperSockets devices that are defined with a smaller MFS (16k, 24k, or 40k) are not affected by this start option. Those devices will use 126 SBALs.
The recommended values can be configured by specifying MAX, AVG, or MIN, which are predefined constants (number of SBALs) that are most appropriate for this type of adapter. MAX allows for the best performance (for example, throughput), but requires more storage. Conversely, MIN could be used for devices with lighter workloads or where system storage might be constrained. Also, instead of using one of the 3 predefined values, users can instead define a specific value for IQDIOSTG (the exact number of SBALs), such as IQDIOSTG=100. The supported range is 8 (minimum supported value) to 126 (maximum supported value). The predefined and possible user defined values for IQDIOSTG are: