ca client get waveform pv error

[wantianmin <wantianmin@gmail.com>]

 Hi all,
I am use a edm client get a waveform pv(640*480 ),the IOC has enough
memory,but only one client can get the pv data,when another client try
to connect to this pv,the client get the error message:
CA value callback('pic1'): No data, CA status The requested data
transfer is greater than available memory or EPICS_CA_MAX_ARRAY_BYTES

But ,I set the EPICS_CA_MAX_ARRAY_BYTES to a big number(1600000000),is
there some other options need to be configured?
Thanks for your help.
wantianmin