Hi Raja,
GL subaccounts concept is used with House Banks & Payment (incoming or outgoing).
In the Chart of Accounts the first digits of GL account are the ones which defines the G/L House Bank Account and the last one is the subaccount
Subacc 0 - Real account
Subacc 1 - Incoming payment
Subacc 2- Outgoing payment
If it's not this, what do you mean by GL subaccounts or what is the scenario you need ??
Kind REgards