The construction where inside the SQL query the assignment with 'INTO' is coded is invalid!
Code:
LET var_query1 = "select ba_action_id into var_ba_action_id from bam_alert_actions where ba_alert_id = var_ar_alert_id and ba_action_id like '" || trim(var_action_occured) || "'";
As far as I know the only valid statements inside a prepared SQL statement are strictly Informix-SQL except for the argument placeholder '?'.
The assignment of an output value into a variable should be done by the EXECUTE statement.
Regards