When executing cryptographic operations against PKCS #11 certificates and keys, System SSL uses the 44-byte handle as defined by ICSF. See 'Introducing PKCS #11 and using PKCS #11 callable services' in z/OS Cryptographic Services ICSF Application Programmer's Guide for the definition of this handle. When using System SSL CMS APIs, the ICSF handle may be referred to as a label, for example, the input private_key_label to Certificate Management Services (CMS) API gsk_make_enveloped_private_key_msg() is the ICSF definition of a handle. The ICSF 44-byte handle is not the same as a PKCS #11 object handle, which is defined as PKCS #11 attribute CK_ULONG.