<str> must specify an unscaled fixed numeric

  Explanation:  The specified quantity must be a fixed numeric
  literal, parameter, or host variable.  This could be the
  position or length of a SUBSTRING.

  User Action:  Change the quantity to be an unscaled fixed
  numeric data type.  If the message specifies SUBSTRING, change
  the position or length of the SUBSTRING to be an unscaled fixed
  numeric data type.