2.9 KiB
description: Configuration items specified in the genesis file
Configuration Items
Network configuration items are specified in the genesis file.
| Item | Description |
|---------------------|-:----------------------------------------------------------------------------------------------------------------------------------------|
| Chain ID | Chain ID for the network |
| Milestone blocks | Milestone blocks for the network |
| ethash | Specifies network uses Ethash and contains [fixeddifficulty](#Fixed Difficulty) |
| clique | Specifies network uses Clique and contains Clique configuration items |
| ibft2 | Specifies network uses IBFT 2.0 and contains IBFT 2.0 configuration items |
| contractSizeLimit | Maximum contract size in bytes. Specify in free gas networks. Default is 24576 and the maximum size is 2147483647. |
| evmStackSize | Maximum stack size. Specify to increase the maximum stack size in private networks with very complex smart contracts. Default is 1024. |
Milestone Blocks
In public networks, the milestone blocks specify the blocks at which the network changed protocol.
!!! example "Ethereum Mainnet Milestone Blocks"
json { "config": { ... "homesteadBlock": 1150000, "daoForkBlock": 1920000, "daoForkSupport": true, "eip150Block": 2463000, "eip150Hash": "0x2086799aeebeae135c246c65021c82b4e15a2c451340993aacfd2751886514f0", "eip155Block": 2675000, "eip158Block": 2675000, "byzantiumBlock": 4370000, "constantinopleBlock": 7280000, "constantinopleFixBlock": 7280000, ... }, }
In private networks, the milestone block defines the protocol version for the network.
!!! example "Private Network Milestone Block"
json { "config": { ... "constantinopleFixBlock": 0, ... }, }
Fixed Difficulty
Use fixeddifficulty to specify a fixed difficulty in private networks using Ethash.
!!! example
```json
{
"config": {
...
"ethash": {
"fixeddifficulty": 1000
},
},
...
}
```