The reason why it happen is explained in the Indirection (@) documentation:

Important:

All variables referenced in the substitution value are public variables, even when used in a procedure.

So, I'd write your method something like:

ClassMethod test() [ PublicList = arg ]
{
    new arg
    s arg = "asd"
    s routine = "say^hello(arg)"
    do @routine
}

In these situations what I use is:

If ##class(Ens.Job).ShouldBeQuiescent() || ##class(Ens.Job).ShouldTerminate() {
    ; close shop!
    Quit
}

VSCode with ObjectScript - tried to run simple MUMPS code and says not supported

Can you provide more details on what and how you tried? It should work, in fact, it does work!

I (and not only me) don't consider it "best practice" but sometime is necessary and I admit I have done it a few times.

You can definitely call another BO from a BO, the only limitation is that you can only make a sync call.

Just use ..SendRequestSync() method, same as you would do in a BP.

What we are seeing is that IRIS.WorkQueue globals are being defined for these calls but then the IRIS.WorkQueue is not being cleaned up and taking up large amounts of Memory.

You mention IRIS.WorkQueue globals consuming/using memory, but globals don't consume memory, they reside on disk.

I never seen any IRIS.WorkQueue globals, can you provide some detail?
What component is creating/using these globals?

Note that, if needed, you can map your classes and global for ALL namespaces currently defined and defined in the future, please check Mapping to All Namespaces documentation on how to use %ALL namespace mapping.

You need to check the Storage defined in your class, typically automatically generated when the class is first compiled.

For example I have created a ConfigUtils.ConfigSettingsTable class:

Class ConfigUtils.ConfigSettingsTable Extends %Persistent
{

Property Name As %String;

Storage Default
{
<Data name="ConfigSettingsTableDefaultData">
<Value name="1">
<Value>%%CLASSNAME</Value>
</Value>
<Value name="2">
<Value>Name</Value>
</Value>
</Data>
<DataLocation>^ConfigUtils.ConfigSetti1ADBD</DataLocation>
<DefaultData>ConfigSettingsTableDefaultData</DefaultData>
<IdLocation>^ConfigUtils.ConfigSetti1ADBD</IdLocation>
<IndexLocation>^ConfigUtils.ConfigSetti1ADBI</IndexLocation>
<StreamLocation>^ConfigUtils.ConfigSetti1ADBS</StreamLocation>
<Type>%Storage.Persistent</Type>
}

}

In this case the globals used by my class are:

^ConfigUtils.ConfigSetti1ADBD (Data)
^ConfigUtils.ConfigSetti1ADBI (Indices)
^ConfigUtils.ConfigSetti1ADBS (Streams)
 

Instead of the 3 single globals, you can map ^ConfigUtils.ConfigSetti1ADB*

Note that you MUST check the actual global(s) name(s) used by your class.

If your class extends another persistent class, then the storage is defined in the superclass that define the extent (the first persistent class in class hierarchy).

In your production class you can implement the OnConfigChange() method.

From Class Reference:

This method is called when config changes to the Production or any item are saved from the portal

To send JSON with an HTTP POST request using InterSystems ObjectScript, you can use the %Net.HttpRequest class. Here is a sample code snippet demonstrating how to do this:

Create an HTTP request object.
Set the server URL and other necessary properties.
Write the JSON payload to the request’s entity body.
Send the POST request.

Here is an example:

Set Body={}
Set Body.Name="John Smith"
Set Body.Address="ISC Dev community"
Set Body.SomeProperty="Some content"
Set Request = ##class(%Net.HttpRequest).%New()
Set Request.Server = "server"
Set Request.Location = "location"
Set Request.ContentType = "application/json"
// Convert the object to JSON and write it to the request's entity body
Do Body.%ToJSON(Request.EntityBody)

// Send the POST request
Set Status = Request.Post()

This is the expected behavior as documented in Message Contents

Management Portal displays only the first 20000 characters of the message by default, this can be changed as documented in Changing the Character Limit for XML Messages in the Contents Tab

So, in your case for only EnsLib.HTTP.GenericMessage you can:

Set ^EnsPortal.Settings("All","MessageContents","OutputSizeLimit","EnsLib.HTTP.GenericMessage")=<whatever size you feel appropriate>

or for any class:

Set ^EnsPortal.Settings("All","MessageContents","OutputSizeLimit")=<whatever size you feel appropriate>

Can you provide more details?

It seems you are using an FTP Outbound adapter, but EnsLib.FTP.OutboundAdapter does not have a property/setting called "Filename".

General answer would be: set the Filename property in you Business Operation code, there you can set it to whatever value you need.