The statement heap is used as a work space for the SQL compiler during compilation of an SQL statement. This parameter specifies the size of this work space.
This area does not stay permanently allocated, but is allocated and released for every SQL statement handled. Note that for dynamic SQL statements, this work area will be used during execution of your program; whereas, for static SQL statements, it is used during the bind process but not during program execution.
Recommendation: In most cases the default value of this parameter will be acceptable. If you have very large SQL statements and the database manager issues an error (that the statement is too complex) when it attempts to optimize a statement, you should increase the value of this parameter in regular increments (such as 256 or 1024) until the error situation is resolved.