Try this one. The idea is, find the state (including the separators), everything before is the city and everything after is the zip code. Then we remove the separator chars (whitespaces, commas and dots).

ClassMethod Disjoin(data, cty, sta, zip)
{
    i $locate(data,"(\s|,|\.)[A-Za-z]{2}(\s|,|\.)",3,,sta) {
        s $lb(cty,zip)=$lfs(data,sta), sta=$$s(sta), cty=$$s(cty), zip=$$s(zip)
        
    } else { s (cty,sta,zip)="" }
    
    q sta]""
    
s(x)	q $zstrip(x,"<>w",",.")
}

Some examples
i ##class(DC.Test).Disjoin("CANTON,TX.,75103",.c,.s,.z) w c,", ",s,", ",z --> CANTON, TX, 75103
i ##class(DC.Test).Disjoin("MILFORD, OH 45150",.c,.s,.z) w c,", ",s,", ",z --> MILFORD, OH, 45150
i ##class(DC.Test).Disjoin("MILFORD OH 45150",.c,.s,.z) w c,", ",s,", ",z --> MILFORD, OH, 45150
i ##class(DC.Test).Disjoin("KANSAS CITY, MO, 12345",.c,.s,.z) w c,", ",s,", ",z --> KANSAS CITY, MO, 12345
i ##class(DC.Test).Disjoin("KANSAS CITY MO, 12345",.c,.s,.z) w c,", ",s,", ",z --> KANSAS CITY, MO, 12345
i ##class(DC.Test).Disjoin("ST. LOUIS MO, 12345",.c,.s,.z) w c,", ",s,", ",z --> ST. LOUIS, MO, 12345
i ##class(DC.Test).Disjoin("  ST. LOUIS MO, 12345",.c,.s,.z) w c,", ",s,", ",z --> ST. LOUIS, MO, 12345

OK, something like this gives a wrong result...
i ##class(DC.Test).Disjoin("   ST. LOUIS MO, 12345",.c,.s,.z) w c,", ",s,", ",z --> , ST, LOUIS MO, 12345

Class DC.Test Extends %RegisteredObject
{
/// Return TRUE if val contains an string
ClassMethod IsString(val) As %Boolean
{
    q $a($lb(val),2)<3
}
/// Return TRUE if val contains a number (int, real or double)
ClassMethod IsNumber(val) As %Boolean
{
    q $a($lb(val),2)>3
}
}

w ##class(DC.Test).IsString("abc") //--> 1
w ##class(DC.Test).IsString("123") //--> 1
w ##class(DC.Test).IsString(123) //--> 0
w ##class(DC.Test).IsNumber(123) //--> 1
w ##class(DC.Test).IsNumber("abc") //--> 0
w ##class(DC.Test).IsNumber("123") //--> 0
w ##class(DC.Test).IsNumber(123_345) //--> 0
w ##class(DC.Test).IsNumber(123+345) //--> 1
w ##class(DC.Test).IsString(123_456) //--> 1
w ##class(DC.Test).IsString(123+456) //--> 0

s x=123, y="123"
w ##class(DC.Test).IsString(x) //--> 0
w ##class(DC.Test).IsString(y) //--> 1

The input variable pInput is an object(reference). You can't save OREFs in a global!

Think about OREFs as memory location (or, if you "speak" C, as a pointer). Trying to save it in a global is the same as saving a C pointer into a file for a later use... Won't work either 

Class My.Class 
{
Property MyProperty As %String [ReadOnly];

Method %OnNew(init As %String) As %Status [ Private, ServerOnly = 1 ]
{
    set i%MyProperty = init
}
} 

And use it as

set obj = ##class(My.Class).%New("Some initial value")
write obj.MyProperty --> Some initial value
set obj.MyProperty --> <CANNOT SET THIS PROPERTY>

A possible work-around could be the class below. In short, you work with your json property as intended, merely before saving the object, you save the json-property into a stream and after opening an instance, you restore the json-property from the the stream - that's all. The drawback, no SQL over the json property...

Class DC.Dyn Extends %Persistent
{
Property json As %DynamicObject [ Transient ];
Property jstr As %GlobalCharacterStream [ Internal, Private ];

ClassMethod MyTest(kill = 0)
{
   if kill do ..%KillExtent(1,1)

   set obj=..%New()
   set obj.json.short="A short test text"
   set obj.json.maxstr=$tr($j("",$$$MaxStringLength)," ","X")
   do obj.json.%Set("hugedata",..stream(obj),"stream")

   write "Status : ",obj.%Save(),!
   set id=obj.%Id()
   write "ID : ",id,!
   kill (id)

   set obj=..%OpenId(id)
   write "short : ",obj.json.short,!
   write "maxstr : ",$e(obj.json.maxstr,1,20),"... Size: ",$length(obj.json.maxstr),!
   set stream=obj.json.%Get("hugedata",,"stream")
   write "hugedata: ",stream.Read(20),"... Size: ",stream.Size,!
}

ClassMethod stream(obj)
{
   set stream=##class(%Stream.TmpCharacter).%New()
   do stream.Write(obj.json.short)
   do stream.Write(obj.json.maxstr)
   do stream.Write(obj.json.maxstr)
   quit stream
}

Method %OnOpen() As %Status [ Private, ServerOnly = 1 ]
{
   if ..jstr {
      do ..jstr.Rewind()
      set ..json=##class(%DynamicAbstractObject).%FromJSON(..jstr)
   }
   Quit $$$OK
}

Method %OnAddToSaveSet(depth As %Integer = 3, insert As %Integer = 0, callcount As %Integer = 0) As %Status [ Private, ServerOnly = 1 ]
{
   do ..jstr.Clear(), ..json.%ToJSON(..jstr)
   Quit $$$OK
}
}

Some testing...

IDEV:USER>d ##class(DC.Dyn).MyTest(1)
Status  : 1
ID      : 1
short   : A short test text
maxstr  : XXXXXXXXXXXXXXXXXXXX... Size: 3641144
hugedata: A short test textXXX... Size: 7282305

If your code uses obj.%Reload() then %OnReload() and %OnOpen() should contain the same code.

- Use stream instead of string or

- shorten the data... ;-))