awk 'BEGIN {
  while((getline < "'${HSLIST}'")>0)    # read all names from the host list
     S[$0]                              # create an instance in the S hash; ="" is implied

  # file should have been closed with close( filename )

  FS="\n"; RS="}\n"                     # after reading host list; change field and record separators
                                        # this effectively causes each block to be one input record
}

/servicestatus {/ && /service_description='${STRING}'/ {    # execute the following code when the input record
                                                            # contains "servicestatus (" and "service_description="
  for(X in D) delete D[X];                                  # delete previous values in D;  delete( D ) is more efficient

  for(N=2; N<=NF; N++)                                      # for each field, starting with 2, (these are name=value pairs)
  {
       split($N, A, "=");                                   # divide the field int array A.  a[1] contains name, a[2] contains the value
       D[A[1]] = A[2]                                       # create an instance in the D hash using the name to map to value
       i = 3;                                               # not in your example input, but this handles the case where the
       while (i in A)                                       # name=value is actually  name=value=more=stuff
          D[A[1]] = D[A[1]] "=" A[i++];                     # by adding more=stuff to the value saved in D[name]
  }

  if (D[" host_name"] in S)                                 # if the hostname sussed from the data was in the file read; print the info
       printf("%s -------- %s -------- %s -------- %s -------- %s -------- %s -------- %s -------- %s\n", D["host_name"], 
   D["service_description"], 
   D["check_execution_time"], 
   D["check_latency"], 
   D["last_check"], 
   D["last_hard_state_change"], 
   D["current_state"],
   D["plugin_output"])

}' $LFILE

awk -v hostf=$HSLIST -v desc=$STRING '
    BEGIN {
        while( (getline < hostf) > 0 )
            hlist[$1];
        close( hostf );                         # good practice to close a file when done with it

        split( "host_name service_description check_execution_time check_latency last_check last_hard_state_change current_state plugin_output", desired, " " );
    }

    /servicestatus {/ { snarf = 1; next; }      # beginning of desired chunk -- start saving info

    /}/ && snarf {
        if( data["host_name"] in hlist )                    # if host was in the list; print its data
        {
            for( i = 1; i <= length( desired ); i++ )       # print desired output; less efficient, but more flexible when adding or changing order
                printf( "%s%s", i > 1 ? " ------- " : "", data[desired[i]] );
            printf( "\n" );
        }
        delete( data );                     # use split( "", data, "." );  if awk version does not support delete()
        snarf = 0;
        next;
    }

    snarf {                                 # saving data; cache value (all after first =) in data hash
        nm = $1;
        gsub( "=.*", "", nm );              # drop everything after first = from name string
        val = $0;
        sub( "^[^=]*=", "", val );          # drop name= from the value string
        data[nm] = val;                     # save it
    }
' input-file