Dynamic SQL With Select Update For

I wrote a simple procedure to copy the create timestamp and create user name to update timestamp and update user name of the same record. (See code below)

This works fine for a hard-coded table and primary key column. However, I cannot figure out how to get this to work with dynamic sql.

All my other procs, which don't use SELECT UPDATE FOR work fine with dynamic sql.

Proc that works:

CODECREATE OR REPLACE PROCEDURE proc_set_upd_columns
IS
CURSOR c1 IS
SELECT *
FROM mytable
FOR UPDATE
ORDER BY mycolumn;
c1rec c1%ROWTYPE;
[code].........

Partial proc that does NOT work:

CODECREATE OR REPLACE PROCEDURE LDEVORE.proc_set_upd_columns (
p_input_table_name IN VARCHAR2,
p_pk_id_col_name IN VARCHAR2)
IS
v_qry_str VARCHAR2(1000);
v_cursor_str VARCHAR2(1000);
v_create_tmstmp TIMESTAMP;
v_create_user_name VARCHAR2(30);
[code].......