| NONE | DB2 does not optimize the access path for SQL statements containing host variables, parameter markers, global variables, or special registers, and uses real values for these variables. Instead, DB2 uses the default estimates for the these variables, caching and using these defaults subsequently. |
| ONCE | When a query is first executed, DB2 optimizes the access path for SQL statements using the real values of the host variables, parameter markers, global variables, or special registers caching and using these real values subsequently. |
| ALWAYS | DB2 compiles and reoptimizes the access path for SQL statements using the values of the host variables, parameter markers, global variables, or special registers known at each execution time. |