Global variables across more than one REXX program

It is not possible to have global variables across more than one REXX 
program in Classic REXX, without the support of external modules that 
provide this capability. (In Object-Oriented REXX, however, such global 
variables are possible; see New features in Object REXX that are useful 
Classic REXX programs). To get around this limitation, a lot of DLLs for 
Classic REXX have been written which contain functions to share global 
variables between REXX programs. 

You may, for example, use the function RxPassByName from the DLL RXU to 
share variables between two or more CMDs: 

"One thing I'd want to emphasize in the description of RxPassByName() is 
that it not only allows one Rexx program to call another, but most 
importantly it allows two Rexx command files (.CMD) to share their 
variable pools in a manner similar to the way the "EXPOSE" instruction 
lets different procedures in a single .CMD file share their variables." 

Dave Boll, Author of RXU (see EMail Addresses) 

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Another way to implement global variables across more than one REXX 
program running in the same session is to use Environment Variables. 

In this case, I suggest you use "read-only" environment variables (see 
Read-only and Write-only environment variables) 

Note:  Be aware that there seems to be a restriction for the maximum 
       length of the contents of an environment variable! 
       If you have environment variables with more than 1024 characters 
       you'll get SYS3175 in CMD.EXE - sooner or later. 

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 A way to implement global variables across more than one REXX program 
 running in different sessions is to use REXX Queues - see  Using REXX 
 queues for global variables for some sample code to use this technique. 

 Be aware that there is no way to get a list of existing REXX queues. 
 Therefore you should not loose the name of your global variables if using 
 this technique. Note also that I don't know how much overhead there is 
 for a REXX queue. 

 Source: Harold Putmann (see EMail Addresses) And 

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 Another method to implement global variables is described in the section 
 Using Persistent Variables.