Help with BEGIN/COMMIT within a transaction

I aplogoize in the first place, if this is a silly question. But as silly as it
sounds it has been giving me a hard time.

I need to use BEGIN/COMMIT within a stored procedure and almost all the syntax
(e.g. BEGIN ... COMMIT, START ... COMMIT, BEGIN WORK ... COMMIT WORK etc.)
gives me an error when I try to execute (not when I compile) the stored
procedure.

Attached is the script to reproduce the problem.

Is there a compile time option or a server setting that I need to enable ?

It does COMMIT when it exits from the stored procedure, but thats not I want. I
want to commit from within a cursor loop so that the changes are visible in
other sessions as soon as they are done.

=== create table script ==
create table employee
(
id integer,
name text
);

=== stored procedure =====

CREATE OR REPLACE FUNCTION sp_test() RETURNS TEXT AS '
BEGIN

START
INSERT INTO employee (id, name) values (1, ''postgres'');
COMMIT;

return ''OK'';

END;

' LANGUAGE plpgsql;

=== invoking the stored procedure thru psql ===

test=# select sp_test() as status;
WARNING: plpgsql: ERROR during compile of sp_test near line 3
ERROR: parse error at or near ";"
test=#

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