Problem adding root files

Dear Root users,
Hi !
I am trying to add four root files containg only one tree in them with the following script :

TString fname1=“56CoFe0808_IPAC_R1.root”;
TString tree1_name=“TREE”;

TString fname2=“56CoFe0808_IPAC_R2.root”;
TString tree2_name=“TREE”;

TString fname3=“56CoFe0808_IPAC_R3.root”;
TString tree3_name=“TREE”;

TString fname4=“56CoFe0808_IPAC_R4.root”;
TString tree4_name=“TREE”;
TFile* f=TFile::Open( fname1.Data(), “READ” );
TTree T = (TTree)f.Get(“tree1_name”);
TFile* f=TFile::Open( fname2.Data(), “READ” );
TTree T = (TTree)f.Get(“tree2_name”);
TFile* f=TFile::Open( fname3.Data(), “READ” );
TTree T = (TTree)f.Get(“tree3_name”);
TFile* f=TFile::Open( fname4.Data(), “READ” );
TTree T = (TTree)f.Get(“tree4_name”);
TChain chain(“TREE”);

The four root files are of the following size :
56CoFe0808_IPAC_R1.root = 427 MB
56CoFe0808_IPAC_R2.root = 837 MB
56CoFe0808_IPAC_R3.root = 686 MB
56CoFe0808_IPAC_R1.root = 804 MB

The merging process is fine with no error.
BUT after generating the output file - ‘result1_4.root’ of size 1.9 GB,
it gives the following message :
" Fill: Switching to new file: chams1_4_1.root "
and start writing in the new file.
I don’t want to get two output files.
My question is -
Is there a limit for the number of entries in a root file in ROOT ?
If yes then how can I increase it to get the result in just one output file .
I am using ROOT 5.17/06 version.
Please reply soon.

Thanks & regards,

[quote]Is there a limit for the number of entries in a root file in ROOT ?
[/quote]There is no absolute limit but the default is set to 2.1Gb of data. See … ChangeFile for details.