Bind command processing and input buffer size

Bind processing uses the LOCATE and CDCINIT value to fill RV1MAXIP in the RVT. This value is used by bind processing to specify z/TPF's maximum input buffer size. This value is the least of:
  • The value in the bind image table for the resource
  • The value in CTK2 that specifies z/TPF's maximum physical input buffer size (the field filled in by SNA Restart)
  • The value of LOCATE and CDCINIT.
To fill in RV1MAXDT, the remote resources maximum input buffer size, bind processing uses the LOCATE and CDCINIT value. This value is less than:
  1. The value in the bind image table for the resource.
  2. The value of LOCATE/CDCINIT

OMT creates PIU segments equal to the remote resources maximum RU size (RV1MAXDT) whenever possible. Because of core block size restrictions, values greater than or less than 4027 bytes may not be honored. OMT constructs segments of 4027 bytes when a value greater than this is found. This allows applications that do not have the capability to chain 1055–byte or 4K blocks to take advantage of NPSI's ability to handle 4K PIUs. For instance, if an application issues ROUTC with an output message in chained 381-byte blocks, OMT packs the output into a 4K block and issues SOUTC of the PIU segment. This significantly reduces the number of PIUs flowing in the SNA network.

You can tune the SNA network performance by updating the z/OS® Communications Server LOGMODE table. z/TPF uses its bind image table as absolute maximum values to prevent you from specifying a value that is too high for z/TPF.