IMPI_C_COLL_XSIZE

Each client contributes an IMPI_Int4 that indicates the minimum number of data bytes for which relevant collective calls will use ``long'' protocols. Relevant collective calls with data sizes less than this value will use ``short'' protocols.

Clients must provide a way for users to choose this value. If the user does not select a value, the client will contribute -1, indicating that that client wants the default value for this label. If the user does select a value (which must be $\ge 0$), that value is sent. All clients must contribute the same value, or an error occurs.

The default value for IMPI_C_COLL_XSIZE for IMPI version 0.0 is 1024.