searching specific text in xmltype column without indexing - ORA-19011

i have over than 1000 tables with same structure, table's structure looks like this:

create table <table_name>

(id varchar2

xmldata xmltype);

i want to search a specific text (like xyz) in all xmldata column in all tables, i used the below script however sometimes i get "ORA-19011: Character string buffer too small", the script im using:

SET SERVEROUTPUT ON
declare
view_list NUMBER(10);
V VARCHAR2(100);
v_sql varchar2(500);
begin

V:='SIM.BATCH.STATUS';

for r in (select object_name from user_objects where object_type='TABLE' and object_name like 'F_%' ESCAPE '' AND ROWNUM<1000) loop

--dbms_output.put_line(R.object_name);