Each OSA-Express QDIO and HiperSockets™ interface requires fixed storage for read processing (which is allocated by VTAM®). If you define a large number of these interfaces (for example, by configuring multiple VLANs to one or more OSA-Express features), then you need to consider how much fixed storage your configuration requires.
For information about how much fixed storage VTAM allocates by default for each OSA-Express QDIO and HiperSockets interface, how to control the amount of this storage allocation using the VTAM QDIOSTG start option (for OSA-Express QDIO) and the VTAM IQDIOSTG start option (for HiperSockets), and considerations for the IVTPRM00 parmlib member, see z/OS Communications Server: SNA Resource Definition Reference.
You can also override the global QDIOSTG or IQDIOSTG value and control the amount of fixed storage for a specific OSA-Express QDIO or HiperSockets interface by using the READSTORAGE parameter on the LINK and INTERFACE statements.