Fn_get_sql , No Full SQL Data

I'm struggling to get anything out of this fn_get_sql() thing as included below.
First, running this in Q.A. still doesn't return the full SQL string, just the first x characters. Second, for most processes the sql_handle in Sysprocesses is just zeroes. Does this info get lost after a while? All the processes where I need to know what happened are old ones, that's waiting for NETWORKIO.


drop proc dbo.getsql
go
create proc dbo.getsql as
begin

declare @sql_handle binary(8000)
select @sql_handle = sql_handle from sysprocesses where spid = 112
-- select spid,sql_handle from sysprocesses where spid = 79
-- PRINT @SQL_HANDLE
SELECT * from ::fn_get_sql(@sql_handle)

end

exec dbo.getsql