SQL Server stored procedure parameter conversion

[INTARYNX]

I am trying to execute a SQL Server stored procedure with a parameter:

SELECT 'table' AS component;
EXEC Test.dbo.TestStoredProcedure $param;

The variable $param contains the right value, but when SQLPage tries to execute the stored procedure, it tries to cast the parameter. However, SQL Server (2017) doesn't allow expressions in the EXECUTE statement, and SQLPage returns the following error:

In "test.sql": The following error occurred while executing an SQL statement:

Error returned from database: Incorrect syntax near '@p1'.
The SQL statement sent by SQLPage was:

EXECUTE Test.dbo.TestStoredProcedure CAST(@p1 AS VARCHAR(MAX));

The error is different from what was reported here: #655

Is there a way to put the $param value in a SQL Server variable before the execution of the stored procedure?

I've tried the following, but it doesn't work:

SELECT 'table' AS component;
SET @p VARCHAR(MAX) = $param;
EXEC Test.dbo.TestStoredProcedure @p;