Locks all the physical libraries in the current virtual library
    list so that they cannot be modified.

    Format

      SCA$LOCK_LIBRARY  command_context

1  –  Argument

 command_context
    type:       $SCA_COMMAND_CONTEXT
    access:     read/write
    mechanism:  by reference

    An SCA command context.

2  –  Condition Value Returned

    SCA$_NORMAL           The libraries have been successfully locked.

3  –  Description

    The SCA$LOCK_LIBRARY routine locks all the physical libraries in
    the current virtual library list so that they cannot be modified.