<PackageReference Include="NETStandard.Library" Version="2.0.0" />

System.Threading.ThreadLocal<T>

public class ThreadLocal<T> : IDisposable
namespace System.Threading { public class ThreadLocal<T> : IDisposable { public bool IsValueCreated { get; } public T Value { get; set; } public IList<T> Values { get; } public ThreadLocal(); public ThreadLocal(bool trackAllValues); public ThreadLocal(Func<T> valueFactory); public ThreadLocal(Func<T> valueFactory, bool trackAllValues); public void Dispose(); protected virtual void Dispose(bool disposing); } }