The host variable in the PREPARE FROM clause must be a string.

  Explanation:  A host variable in the FROM clause of a PREPARE
  statement must have a string data type.

  User Action:  In COBOL declare the variable to be PIC X(n).  In
  PL/I declare the variable to be CHAR(n).  In FORTRAN, declare
  the variable to be CHARACTER XYZ*n.