All host variables used in SQL statements must be explicitly declared.
The PL/I statements that are used to define the host variables should be preceded by a BEGIN DECLARE SECTION statement and followed by an END DECLARE SECTION statement. If a BEGIN DECLARE SECTION and END DECLARE SECTION are specified, all host variable declarations used in SQL statements must be between the BEGIN DECLARE SECTION and the END DECLARE SECTION statements.
All host variables within an SQL statement must be preceded by a colon (:).
The names of host variables must be unique within the program, even if the host variables are in different blocks or procedures.
An SQL statement that uses a host variable must be within the scope of the statement in which the variable was declared.
Host variables must be scalar variables. They cannot be elements of an array.