EDITED 2019-02-08

`maxTxFee` is a global variable, used by both the raw transaction and wallet RPCs. It's set from `-maxtxfee`.

~listed in the global help text in init.cpp, but is only set in `WalletInit::ParameterInteraction()`. If the wallet is disabled, then `-maxtxfee` is ignored and the default is used.~

~This behaviour has existed since the mempool was changed to limit acceptance based on `maxTxFee` in https://github.com/bitcoin/bitcoin/commit/fa331db68bcc68e4c93fb45aaa30f911b0ecfe1a.~

~Short-term fix is to move the `-maxtxfee` handling to `InitParameterInteraction()` in init.cpp.~
EDIT: `maxTxFee` initiation bug fixed in #15357 

I don't think we should share this setting between the node and wallet.
gArgs.AddArg("-printtoconsole", "Send trace/debug info to console (default: 1 when no -daemon. To disable logging to file, set -nodebuglogfile)", false, OptionsCategory::DEBUG_TEST);
    gArgs.AddArg("-shrinkdebugfile", "Shrink debug.log file on client startup (default: 1 when no -debug)", false, OptionsCategory::DEBUG_TEST);
    gArgs.AddArg("-uacomment=<cmt>", "Append comment to the user agent string", false, OptionsCategory::DEBUG_TEST);
    SetupChainParamsBaseOptions();
    gArgs.AddArg("-acceptnonstdtxn", strprintf("Relay and mine \"non-standard\" transactions (%sdefault: %u)", "testnet/regtest only; ", !testnetChainParams->RequireStandard()), true, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-incrementalrelayfee=<amt>", strprintf("Fee rate (in %s/kB) used to define cost of relay, used for mempool limiting and BIP 125 replacement. (default: %s)", CURRENCY_UNIT, FormatMoney(DEFAULT_INCREMENTAL_RELAY_FEE)), true, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-dustrelayfee=<amt>", strprintf("Fee rate (in %s/kB) used to defined dust, the value of an output such that it will cost more than its value in fees at this fee rate to spend it. (default: %s)", CURRENCY_UNIT, FormatMoney(DUST_RELAY_TX_FEE)), true, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-bytespersigop", strprintf("Equivalent bytes per sigop in transactions for relay and mining (default: %u)", DEFAULT_BYTES_PER_SIGOP), false, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-datacarrier", strprintf("Relay and mine data carrier transactions (default: %u)", DEFAULT_ACCEPT_DATACARRIER), false, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-datacarriersize", strprintf("Maximum size of data in data carrier transactions we relay and mine (default: %u)", MAX_OP_RETURN_RELAY), false, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-mempoolreplacement", strprintf("Enable transaction replacement in the memory pool (default: %u)", DEFAULT_ENABLE_REPLACEMENT), false, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-minrelaytxfee=<amt>", strprintf("Fees (in %s/kB) smaller than this are considered zero fee for relaying, mining and transaction creation (default: %s)",
        CURRENCY_UNIT, FormatMoney(DEFAULT_MIN_RELAY_TX_FEE)), false, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-whitelistforcerelay", strprintf("Force relay of transactions from whitelisted peers even if they violate local relay policy (default: %d)", DEFAULT_WHITELISTFORCERELAY), false, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-whitelistrelay", strprintf("Accept relayed transactions received from whitelisted peers even when not relaying transactions (default: %d)", DEFAULT_WHITELISTRELAY), false, OptionsCategory::NODE_RELAY);
    gArgs.AddArg("-blockmaxweight=<n>", strprintf("Set maximum BIP141 block weight (default: %d)", DEFAULT_BLOCK_MAX_WEIGHT), false, OptionsCategory::BLOCK_CREATION);
    gArgs.AddArg("-blockmintxfee=<amt>", strprintf("Set lowest fee rate (in %s/kB) for transactions to be included in block creation. (default: %s)", CURRENCY_UNIT, FormatMoney(DEFAULT_BLOCK_MIN_TX_FEE)), false, OptionsCategory::BLOCK_CREATION);
    gArgs.AddArg("-blockversion=<n>", "Override block version to test forking scenarios", true, OptionsCategory::BLOCK_CREATION);
    gArgs.AddArg("-rest", strprintf("Accept public REST requests (default: %u)", DEFAULT_REST_ENABLE), false, OptionsCategory::RPC);
    gArgs.AddArg("-rpcallowip=<ip>", "Allow JSON-RPC connections from specified source. Valid for <ip> are a single IP (e.g. 1.2.3.4), a network/netmask (e.g. 1.2.3.4/255.255.255.0) or a network/CIDR (e.g. 1.2.3.4/24). This option can be specified multiple times", false, OptionsCategory::RPC);
    gArgs.AddArg("-rpcauth=<userpw>", "Username and HMAC-SHA-256 hashed password for JSON-RPC connections. The field <userpw> comes in the format: <USERNAME>:<SALT>$<HASH>. A canonical python script is included in share/rpcauth. The client then connects normally using the rpcuser=<USERNAME>/rpcpassword=<PASSWORD> pair of arguments. This option can be specified multiple times", false, OptionsCategory::RPC);
    gArgs.AddArg("-rpcbind=<addr>[:port]", "Bind to given address to listen for JSON-RPC connections. Do not expose the RPC server to untrusted networks such as the public internet! This option is ignored unless -rpcallowip is also passed. Port is optional and overrides -rpcport. Use [host]:port notation for IPv6. This option can be specified multiple times (default: 127.0.0.1 and ::1 i.e., localhost)", false, OptionsCategory::RPC);
    gArgs.AddArg("-rpccookiefile=<loc>", "Location of the auth cookie. Relative paths will be prefixed by a net-specific datadir location. (default: data dir)", false, OptionsCategory::RPC);
    gArgs.AddArg("-rpcpassword=<pw>", "Password for JSON-RPC connections", false, OptionsCategory::RPC);
    gArgs.AddArg("-rpcport=<port>", strprintf("Listen for JSON-RPC connections on <port> (default: %u, testnet: %u, regtest: %u)", defaultBaseParams->RPCPort(), testnetBaseParams->RPCPort(), regtestBaseParams->RPCPort()), false, OptionsCategory::RPC);
    gArgs.AddArg("-rpcserialversion", strprintf("Sets the serialization of raw transaction or block hex returned in non-verbose mode, non-segwit(0) or segwit(1) (default: %d)", DEFAULT_RPC_SERIALIZE_VERSION), false, OptionsCategory::RPC);
    gArgs.AddArg("-rpcservertimeout=<n>", strprintf("Timeout during HTTP requests (default: %d)", DEFAULT_HTTP_SERVER_TIMEOUT), true, OptionsCategory::RPC);
    gArgs.AddArg("-rpcthreads=<n>", strprintf("Set the number of threads to service RPC calls (default: %d)", DEFAULT_HTTP_THREADS), false, OptionsCategory::RPC);
    gArgs.AddArg("-rpcuser=<user>", "Username for JSON-RPC connections", false, OptionsCategory::RPC);
    gArgs.AddArg("-rpcworkqueue=<n>", strprintf("Set the depth of the work queue to service RPC calls (default: %d)", DEFAULT_HTTP_WORKQUEUE), true, OptionsCategory::RPC);