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.
if (net == NET_UNROUTABLE)
                return InitError(strprintf(_("Unknown network specified in -onlynet: '%s'"), snet));
            nets.insert(net);
        }
        for (int n = 0; n < NET_MAX; n++) {
            enum Network net = (enum Network)n;
            if (!nets.count(net))
                SetReachable(net, false);
        }
    }
    
    fNameLookup = gArgs.GetBoolArg("-dns", DEFAULT_NAME_LOOKUP);
    bool proxyRandomize = gArgs.GetBoolArg("-proxyrandomize", DEFAULT_PROXYRANDOMIZE);
    
    
    std::string proxyArg = gArgs.GetArg("-proxy", "");
    SetReachable(NET_ONION, false);
    if (proxyArg != "" && proxyArg != "0") {
        CService proxyAddr;
        if (!Lookup(proxyArg.c_str(), proxyAddr, 9050, fNameLookup)) {
            return InitError(strprintf(_("Invalid -proxy address or hostname: '%s'"), proxyArg));
        }
        proxyType addrProxy = proxyType(proxyAddr, proxyRandomize);
        if (!addrProxy.IsValid())
            return InitError(strprintf(_("Invalid -proxy address or hostname: '%s'"), proxyArg));
        SetProxy(NET_IPV4, addrProxy);
        SetProxy(NET_IPV6, addrProxy);
        SetProxy(NET_ONION, addrProxy);
        SetNameProxy(addrProxy);